They're surprisingly adventurous critters, even when hostless, but when they're riding around on a human's head, they are fearless. Dangerous in a fight, they rarely stay in one place, leaping from head to head in the fray, staying one enemy's sword, misdirecting an arrow on the next, interrupting spells and generally busting heads.
They're very fond of humans and never have understood the distrust they suffer, although they're also notoriously... unsentimental about their hosts, with little regard for their safety or well-being. You might say they're fond of humans in the same sense humans are fond of particularly ornate wrenches.
A Weird Hero, the Jelly Tyrant can be played in two ways: one, as a mind-controller that coerces a player character to obey his commands, or two, as a cooperative master who directs a mini-party of himself and a willing thrall. For the coerced victim, he may periodically trade out hosts, superimposing skills and bonuses he has onto the template of various NPCs he controls.