Initially a remorseless hunter in a pack of other sabers, Diego was to deliver a human baby to his pack leader, Soto, as revenge upon the humans. During his interception of the child, Diego met a mammoth named Manfred and a sloth named Sid, who had already taken the child and, in time, convinced the saber to leave his old pack and join up with them as part of the herd.
Some time later, Diego and his herd resided in a valley that would soon flood over, due to the large amounts of melting ice. As the herd journeyed along with the other herds of animals, they met a female mammoth named Ellie, who lived with her adopted possum brothers Crash and Eddie. Manny, through Sid's urgings, took Ellie as a wife, making her and her possum brothers new members of the herd.
Within time, Diego grew upset with his complacent life in a herd, having lost his edge as a hunter and so considered leaving his herd behind, rejoining them as they went out on a search for Sid, who had taken three dinosaur eggs as his adopted children. After time, Diego stayed with his herd and returned to their own world.
Years later, Diego remained a member the herd and stayed with them through it all, though he, along with Manny and Sid, was separated from their herd as ongoing continental drift divided them, the four going on to meet a group of animal pirates, and among them was a female saber named Shira that caught Diego's eye. In time, Diego convinced Shira to leave her pirate crew-mates behind and join Diego's herd as his girlfriend when the herd left their old home to find a new one due to the continents shifting.
A gruff saber-toothed cat, Diego had a change of lifestyle, leaving the pack he once ran with to join a ragtag herd of animals. Through this, Diego learned to be caring, gentle and not as quick to anger.
As a cub, Diego was brought up in a pack with other sabers, including his father. Diego's father, being an adept hunter, would bring back a gazelle for Christmas as a feast for the whole family.
At some juncture in the past, a pack of humans had attacked Diego's pack, taking the lives of half of them so as to use their skins to fashion warm clothing. Soto, the pack leader, was driven furious by this, choosing to exact revenge by killing and devouring the pack leader's baby, Roshan. Diego, being appointed Soto's lieutenant, agreed to assemble the pack for an oncoming attack at dawn, also motivated by revenge.
That evening, the others in the pack, Zeke, Lenny and Oscar, all balked at their leader's fixation with the human pack, wondering why they could not follow the animal herd migrations heading south, but Diego asserted his leader's decisions, despite his pack-mates deriding him for it, asking why they couldn't take orders from Soto himself. Soto then appeared, asserting that they followed Diego's orders because Diego was the only saber that Soto trusted. Soto maintained that the attack on the humans would give them all a chance to teach the humans a lesson.
Ambush on the Humans
Early the following morning, the pack moved on for an ambush on the humans' camp. As the sabers moved in to attack, the tribe's dogs barked and alerted the humans to the sabers' presence, the humans led by their chief, a man named Runar. While Soto and the others engaged the humans and their dogs in a fight, Diego crept into the human leader's tent, where he found the baby, sleeping in his bed.
As Diego moved in on his target, the chief's wife, Nadia, quickly grabbed her son out of the bed and struck at the saber with a club. The woman then fled the tent as the men of the tribe fought the sabers, with Diego in hot pursuit as he chased her away from the camp. Diego chased Nadia away from the camp and through a stream, lashing out at her, hitting only the baby's charm necklace, which he swatted away onto the ground and continued to give chase. He then succeeded in chasing Nadia onto a rocky ledge atop a waterfall where, holding her baby closely, Nadia was cornered. As Diego moved in closer, Nadia, holding her baby tightly, jumped from the rock down the waterfall.
Having failed to retrieve the baby, Diego headed back to Soto, who was angered to hear that Diego had lost it over the falls. Before either could say much more, a spear was thrown at the sabers, and Soto led his pack away, with Diego stating that he'd find the baby, to which Soto retorted that Diego had best find it or serve himself as a replacement; the pack then agreed to regroup at Half Peak, where Diego was to produce the baby, alive and well. As the others in his pack were chased off by the humans, Diego left to find the baby.
When Diego found the baby, he saw it with Manny and Sid. After unsuccessfully trying to convince them that the baby was his, Diego offered to help lead them to the humans.
After a fight with some Dodos over food,the group went to sleep for the night. Diego attempted to take the baby, but Manny had it wrapped up tightly in his trunk. Diego then realised he was being watched. He pounced, only to find Oscar and Zeke. Diego told them that he was bringing Soto both the baby and Manny.
The next day, Diego was awoken abrubtly by Manny, who thought he had taken the missing baby (It turned out Sid took him to impress some ladies). Shortly after,Sid, running from a pair of rhinos, begged Diego to pretend to eat him. Diego turned away in disgust, but a kick from Sid changed his mind. He held the sloth in his jaws, convincing the rhinos he was dead, and only spat him out when Manny and the baby came by. When Sid said he thought Diego was going to eat him, the saber coldly replied "I don't eat junk food."
The group continued on their journey, Diego doing everything he could to keep Manny from finding the humans. He even lead to an Ice Cavern, claiming it was a shortcut. Sid voiced his refusal, and Diego's angry rebuttal caused an avalanche, forcing inside. Once inside, the baby slipped away from them. During the chase, Diego tried to get the baby, but was beaten to him by Manny. Afterwards, they came across a tunnel filled with cave paintings.
Not long after going outside, the group was caught in an underground eruption. Diego almost fell into a river of lava, but was saved by Manny, who almost died in the process. Confused, Diego asked Manny why he did it. Manny replied "That's what you do in a herd," touching Diego deeply. That night, they took shelter in a cave. The baby started to walk, and, despite Diego's protests, walked over to him.
The next morning, Diego stopped Manny and Sid from going further, revealing that there was an ambush waiting at the bottom of Half Peak, and convinced them to let him help.
When Soto's pack attacked, Diego came to Manny's defense, but was wounded. Unable to move, he told Manny and Sid to keep moving, so that the baby could be reunited with his father. Diego's wounds weren't as bad as they seemed, however, and he recovered in time to say goodbye to the baby and reunite with Manny and Sid. The three of them decided to follow the herds south.
Some time later, the trio had taken up resident near a water park. After saving Sid from a foolhardy attempt to impress others, they discovered that the ice dam was about to break.
As the animals fled to a Boat at the end of the valley, the herd picked up three new members: the possums Crash and Eddie, and Ellie, a mammoth who thought she was a possum. Along the way, they were attacked by Cretaceous and Maelstrom, Diego's fear of water revealing itself. Sid later attempted to talk to Diego about it, but Diego refused.
As the journey continued, Ellie discovered her true identity, but had a falling-out with Manny. When the group were in danger, it was Diego who convinced her to bury the hatchet in order to save everyone.
As they neared the boat, Ellie and the possums seperated from them, but Crash and Eddie returned, teling them she was trapped. As the dam broke and flooded the valley, Diego overcame his fear of water to save Sid, Crash and Eddie, while Manny saved Ellie. Afterwards, the arrival of a mammoth herd made it seem like Manny and Ellie would leave with them, but the grup stuck together, Diego giving Crash and Eddie a ride on his back.
Dawn of the Dinosaurs
Some time later, after the animals had settled into a new home, and Manny and Ellie were expecting a child, Diego found himself unable to catch an Elk. Believing he had lost his edge. Diego decided to leave the herd and go out on his own, a decision that angered Manny.
Just as as he was leaving, Diego saw Sid being carried away by a T-Rex, and followed the rest of the herd in a rescue attempt, which led them into an underground world where Dinosaurs still existed. They were attacked soon after, but saved by a deranged weasel called Buck, who was convinced to help them search for Sid. Along the way, Diego, alongside Crash and Eddie, developed an admiration for Buck's survival skills, and Diego contemplated staying in the dinosaur's cavern.
As the group started to close in on Sid, Ellie went into labour, and was targeted by a pack of Guanlongs. Diego leapt to her defense, keeping the dinosaurs away from her until Manny arrived. Moments later, the baby was born, elicting a tear of joy from Diego. At the same time, Sid had been saved by Buck, Crash and Eddie.
As they made their way out of the cavern, they were attacked by Rudy. Diego, Manny and Sid helped Buck fight the Baronyx, with Momma Dino helping by pushing him off a cliff. As they reached the entrance to the cavern, Buck heard Rudy's roar, and decided to stay. Diego informed the others that Buck was "where he wants to be." As Peaches was introduced to her home, Diego reconciled with Manny, declaring that the life of adventure he sought was right there.
Some years later, Diego, back at the top of his game, was scaling a mountain when he heard the ground rumble. He laughed it off, only to get caught in a Sloth family's log car. As the log came close to hitting Peaches, Diego manages to stop it, and angrily decided to eat one of the sloths, only stopping when Sid recognised him as his Uncle Fungus. Diego and Manny looked on as Sid's family dumped Granny on him, then quickly left, with Diego remarking "That explains a lot about Sid." After breaking the news to Sid, they realised Granny had disappeared.
During the search, Manny got into an argument with Peaches. As the argument went on, there was another rumble. The ground broke apart, seperating Diego, Sid and Manny from Ellie and Peaches. Diego stopped Manny from trying to jump across the gap, pointing out to the irate mammoth that he wouldn't have made it. The chunk of ground they were on floated out to sea, despite their attempts to turn it around.After weathering a storm, they discovered that Granny had inadvertantly come with them, having been sleeping inside a tree that was part of the chunk of land that broke off.
Soon after, they were accosted by a crew of Pirates, who declared their intention to take their "vessel." During the scuffle, Diego was confronted by Shira, telling her "I don't fight girls." Shira distracted him witha cheap shot and pinned him, snarking "I can see why." The herd were taken to the pirates' ship, where their leader, Gutt, tried to convince them to join. When Manny refused, Gutt decided to have Sid and Granny fed to his pet Narwhals. While the crew watched, Diego and Manny escaped, and went to save their friends. In the ensuing scuffle, the pirates' iceberg was destroyed. The herd found a piece of ice to ride on. They saved Shira, who was less then happy at their actions.
Some time later, Sid accidentally made a crack in the ice. Fortunately, an island was nearby, and the group paddled toward it. Shira attempted to make a run for it, but Diego gave chase, and caught her. He then discovered that Gutt and his crew were also on the island. Shira was imprisoned in a tree, and Sid enlisted the help of the island's native Hyrax. That night, Diego brought Shira some water, and learned that she left her pack as he did his. He then pointed out that, unlike her, he hadn't traded one pack for another, and added that Gutt hadn't even bothered to look for her.
The next morning, the group saw that Shira had escaped, and went ahead with their plan to steal Gutt's new ship. While Manny and the Hyrax distracted the pirates, Diego freed their captives. As the pirates came after them, the herd ran toward the ship. Shira tackled Diego. Diego asked her why she was doing it. When Shira responded that she had no choice, Diego convnced her to come with him, telling her that he and the others took care of each other. However, Shira stayed behind to slow down Gutt, leaving Diego saddened.
As the herd floated back to the continent, Manny and Sid realised Diego was in love with Shira, and teased him for it. They then encountered Sirens, one of whom took the appearance of Shira to lure Diego in. Manny managed to get them to safety.
Finally returning to the continent, the herd found that Gutt had got there first, and taken the other animals hostage. In the battle that ensued, Shira joined the herd in their fight. After the pirates were defeated, Diego personally welcomed Shira into the herd. Together, the animals travelled to a new home.
Personality and Traits
As a saber-tooth cat, Diego was made for action, with a usually curt demeanor: short for words, Diego was not one to be trifled with. Initially a sharp hunter and a harsh speaker, Diego's demeanor softened as he joined a herd with Manny and Sid. Loyal to the herd, Diego was always one to step in and take action, but did not appreciate being made light of: Sid would often joke with him, to Diego's displeasure, but Diego would never attack anyone. Though Diego lived with other herbivorous animals, he curbed his natural instincts as a hunter and lived in peace with other animals and only hunted when necessary. His composure, however, was shaken when he met Shira, who caught his eye and won him over.
Diego was built like other sabers, with a compact, muscular build and powerful running legs, retractable claws on all four paws, a short set of ears and tail, and, most notably, his set of long canine teeth, with which he hunted other animals. Diego's pelt was burnt orange with a lighter underbelly and light facial fur, and with a short brown mane along his neck and upper back. Diego's eyes were vivid green and were ideal for hunting or looking out at night, as in the darkness they would glow brighter like other cats' eyes.
Behind the Scenes
The initial plan with Diego was that he would die in the first Ice Age film: when younger test audiences saw this, they burst into tears, and so the directors decided to let Diego live.