The ultimate hurdle people face when having to rp an antag is that their character is likely not someone who'd rob the vault, or suck someone's blood until they died, or would take a hostage. Rolling an antag role, these people often take to being "peaceful antags" and while taking your ling ass to xenobiology to serve as research is interesting for the xenobiologist, it doesn't fulfill the concept behind antags, which is to serve as an opposing force to the crew, so I thought I'd leave a few of the ideas I've come up with while rolling antag as Charlie Medley for almost a month straight because i had my antag on.
Nice guy: You recieve the vampirism at the beginning of the shift, and don't want to hurt anyone terribly, you spend the shift doing favors for blood and buying it if necessary, just so you don't hulk out and hurt someone. You talk incessintly about your blood condition, but are careful to ask permission, even in form of a written contract, before drinking.
Possessed: Somehow, your form was taken over by a demon from beyond the veil, and now you play as the parasite within the host. Do some exorcist style me:'s like floating above the ground an inch or two, imitating other people's voices flawlessly, or other spooky demon shit. The best thing about this approach is that it let's you ignore the present character you usually play and allows you to go full evil without painting your character as hiding these dark emotions/desires.
Not really sure what's going on: I did this as my first real cult round, basically, the idea is you know you joined a club, but that's about it. You just kinda go along with what the other people want cause you're all friends and you want to support them, even if what they want is a little whack. You dont know much about the horrible entity you're supposed to be worshipping because you didnt do the assigned reading. You offer little tidbits of "hey sorry man, kinda shit luck they chose you" to your captives and maybe even share a sandwich with them before they get ritually sacrificed. Basically, play your nice, snowflake character, but they just fell in with a bad crowd, and are too introverted to leave.
They've got my family: the reason you've been selected for this mission is unclear, but the Syndicate has shown irrifutable evidence that they have your family as hostage if you don't fulfill it. This offers a wide variety of character concept exploration options, such as who they think is more expendable, who they wouldn't hurt and who they would, whether they'd fire upon security or not in a pinch.
It was me the whole time: you're not actually your character, but a deep cover syndicate operative who's killed them and taken their identity. This allows you to forfet your character concept and possibly kill former friends and allies in a shocking twist. You could even be a "Salt" style sleeper agent, waking up on the station only to realise your purpose for being there was this specific shift, and everyone you've come to love and trust has been a lie, a fabrication.
An unexpected journey: this one is an idea ive had for a while, but never been able to utilize as ive never rolled wiz. The idea is you ask the admin/mod if you could get some co-antags, and then get the go ahead. You then go to the bar, grab some ales, and advertise you are looking to form an adventuring party. Gather up the people that show and arm them with a variety of medieval weaponry (admins willing) or makeshift weaponry if not. Then, start small, killing mice in the tunnels, fetch quests from cargo, then go big, freeing the station from the tyrant (insert head of department here) or looting the abandoned vault and it's hoard of plenty. The solo alt of this is you play yourself as an adventurer and slowly up the antie.
All I can think of atm, anyone else got something?