The ongoing feud between these two has lasted five years
Chosen Juan is the apparent brother of Tintin who is the Chosen One because he stands up to Mr. Rage. He is a member of the Maths Mafia and a Quiffling host, and is said to own the legendary Golden Crossbow, a weapon coverted by Rage. Juan also enjoys attempted to flirt with women, or 'Females', to no avail, often resulting in his face being covered in mud, cake or poo (from one time when he tangled with Shitmaster's sister)
Juan is a victim. He is bullied by everyone: his parents, Mr. Rage, the other members of the Mafia, himself, his Quifflings, Females, even his own inflatable wife bullies him. Poor guy.
But don't feel too sorry for him, since he is, after all, a member of the Mafia. He summoned an army of Quifflings to aid him in his endeavours, and with Mafia help, he did eventually manage to kill Mr. Rage in the Duel for the Golden Crossbow, but commited Seppuku soon afterwards as both his inflatable Bride and his Crossbow were destroyed.