Tulio appears to be more the sensible and practical one, with Miguel being more of a dreamer. He is also very sarcastic and tends to boss Miguel around. Tulio is the more anxious member of the duo, at one point telling Miguel that "you can never worry too much."
Role in Film
Both Tulio and Miguel are first seen on a wanted poster, presumably for their occupations: con artists. He is first seen rolling loaded dice (the number 7) to win a bet from a group of sailors. When a sailor, Zaragoza, bet the map to El Dorado, Tulio was disinterested, but quickly pressured into agreeing by Miguel. To make matters worse, Zaragoza demands Tulio use his (Zaragoza's) dice. Tulio ironically wins the bet fairly, however, the event ends on a sour note, as his loaded dice fall from his pocket, discovered by Zaragoza. Tulio and Miguel fake a duel and eventually flee from trouble with the sailors (and the guards), only to be pursued by an angered bull, and eventually the townspeople, and the guards. The duo hides in a pair of barrels that end up being shipped onto Cortés' ship that was destined to depart for the New World. The duo break free from their barrel confinement, only to be found by the sailors on board and consequently, are locked up in the brig.
Miguel uses an apple to convince Altivo, Cortés' horse, to find a pry bar to help them break free; only to be given a set of keys instead, much to Tulio's irritation. Tulio and Miguel then hijack a rowboat, rescue Altivo (who was trying to get the apple) from drowning, and intend to row off to Spain. After few days spent out at sea, with minimal, if no, rations or drinking water, they eventually find land. Overjoyed, they flee from their rowboat, only to be frightened at the sight of skeletons laying about on shore. As Tulio and Altivo run to the boat, Miguel spots a familiar landmark that matches the drawing depicted on the map of El Dorado. Angered at first, that Miguel had chosen to bring the map, Tulio is eventually persuaded by the thought of gold, that he agrees to join the overly excited Miguel on a journey to find the lost city. Meeting Bibo, an armadillo they managed to unknowingly rescue from a predatory snake, along the way, they find the journey to be perilous, facing various issues along the way (mostly Tulio). As they near their destination, Tulio becomes more enthused by the idea, however, once they manage to fall down a cliff, landing before the last landmark, he returns to his irritable self. Seeing nothing but the waterfall behind the last stone, he believes that they've travelled all that way for nothing.
Convinced that nothing lay beyond the stone, Tulio demanded Miguel get on the horse (Altivo), and intended to depart back the way they came, before a native woman runs into them: Chel. The guards, that had apparently been chasing her, corner the Spanish men, before forcing the group to follow them back to El Dorado. Initially, the pair is ecstatic, and amazed, that the legendary city exists, however, their moods quickly change, since they expect to be executed. Once they reach the centre of the city, they are greeted by the high priest, Tzekel-Kan and Chief Tannabok, who, along with the citizens of El Dorado, believe the pair are gods. Tzekel-Kan demands the gods prove their glorious title before Tulio pulls Miguel aside for a quick talk. Annoyed by Miguel's proclamations, he attempts to think of a plan to get them out of their situation. Meanwhile, a volcano begins to erupt, frightening the surrounding people. Panicked, Miguel begins to smack Tulio in the head, only furthering his irritation, before he exclaims, "STOP!". By coincidence, the erupting volcano stops, and the people are convinced, by the sign, that they are truly gods. After being lead up to their temple, and seemingly left alone, Tulio and Miguel laugh, bewildered and amused that the people bought their faux identities. Later, Chel appears, only to make a deal to keep their scam a secret, only if she can join in. The pair, Tulio more so, reluctantly agree.
During their stay in El Dorado, Tulio becomes attracted to the girl, Chel (which Chel reciprocates), which eventually leads to them getting together, despite Tulio and Miguel having agreed that she was off-limits and her age. Miguel eventually finds out, which cements his desire to stay in El Dorado, while Tulio wanted to return to Spain. However, when Cortés and his men are closing in on the city, Tulio comes up with a plan to knock down the pillars, which would help seal the entrance to El Dorado forever. Miguel joins them, last minute, and they successfully see through his plan, losing their golden treasures in the process (much to Tulio's dismay) and run off with Chel and Altivo to find new adventures and a way back to Spain.