CANON POINT: Between chapters 205 and 206, shortly after Allen's departure from the Black Order.
Backtagging: Yes! I can end up being slow as a pancake with my threads due to real-life obligations, so people who take time and patience to finish the thread are greatly appreciated.
Threadhopping: Please, ask for permission first.
Fourthwalling: I'd rather not have that unless it's on memes and I'm warned in advance.
Offensive subjects (elaborate): That heavily depends on the subject. I don't mind discussing controversial subjects as long as you're prepared for a healthy debate, but I can get heated about them, so it's best to be careful about it. In addition, it's best to never bring up the topics of alcoholism and family abuse around him. Both are very bad triggers.
Hugging this character: Yes, but expect Allen to act very flustered about it.
Kissing this character: Yes, and expect Allen to act extremely flustered about it.
Flirting with this character: Yes, but only women will be flirted with back.
Fighting with this character: Yes! However, Allen is very pacifistic and will try to defuse the fight as fast as possible in most cases.
Injuring this character (include limits and severity): No severe life-threatening injury unless you've consulted me before, and we'll be fine.
Killing this character: Maybe in some cases of carefully arranged plot, but mostly no.
Using telepathy/mind reading abilities on this character: Ask first and tell me what you're looking for, please!
KINKS & PREFERENCES
I don't have a general kink list set up yet, but the general rule is that I'm alright with anything that isn't bathroom play, force feeding, vore, weight gain and messy things. I can do non-con, but only with people I played with a lot before and trust completely about it.
For anything else, ask me if you have any doubts.