1) AU, post-war. For the first time since Lily Potter, Snape falls in love - with the most unlikely person. No one believes him and even the man (slash, please, and no Trio) of his dreams thinks he is making fun of him when he finally declares himself.
2) AU, post-war. Arguing with the clerk in Flourish and Blott's over a contract on a purchase of a sizeable amount of books makes Severus draw his wand to hex the man. Unfortunately the spell backfires and instead of doing something nasty to the innocent clerk, it bonds Severus to an innocent bystander.
3) AU, post-war. Severus had a mid-life crisis. He buys the fastest high-end broom, he dresses a bit too youthfully, and he quits his job to go looking for a nice witch to do whatever one does with witches. Only Severus hadn't realised one thing about himself - one thing that makes it impossible to be with a witch at all.
4) Severus decides to face his werewolf phobia.
5) AU, post-war. Malfoy Manor has always been a refuge for Severus, even from he was young. Voldemort ruined that when he took over the mansion. Now the Malfoys try to build up their lives and find their place in a changed word, but where is Severus' place in all this?
Luciucentric:
6) The war ruined things for Lucius. He sits back, watching his brilliant wife manage his life, and realises this is not what he wants. He decides to turn back to the lover he had as a young man, before Narcissa. (AU with /Snape would be a big bonus here!)
7) After time in Azkaban, Lucius has to face the fact that Narcissa and he are almost strangers to each other. He wants them to fall back in love. But how?
8) AU, post-war. Being a widower, the Minister for Magic suggest that Lucius marries again. He is not interested, but agrees for political reasons, then looks for someone he can pay to do it and then leave him alone.
9) AU, post-war. Both Potter and Voldemort dies in the battle. Suddenly Lucius (rather confused) finds himself as the new Dark Lord.
10) SS/LM AU, post-war: Severus and Lucius had planned to leave the wizarding world after Voldemort's fall. But everything went wrong. Unbeknownst to Lucius, Severus is in a Muggle hospital, and Lucius is at home, trying to find a way to keep his promises to Severus, dead or alive. Happy end a plus!