Many things come to mind. Convincing child characters, great rhetoricians (while still maintaining a pace that doesn't put your follow players to sleep) or someone deeply spiritual without ending up in cliché. But if I had to pick one, I'd say I go for
building trust.
Having build some real, meaningful trust of your avatar in the character of someone else and being rewarded with that same level of trust in return. It is something that is often futile due to the nature of the medium, with players not seeing each other every day (or at the very least not maintaining the same characters as often as they are online for Lismore RP). Character relations are often erratic, more befitting any present scenario's needs than what was slowly build up in the days, weeks or months before. Establishing that against the odds and maintaining it throughout what events or scenes are thrown your way would make me one proud and happy wolf indeed.
@ShaRroos: No commenting unless you offer us your reply as well.