REC: Drake of Dross's mpreg stories
The website is here. There are several Snape mpregs (my favorites are the "Twice" stories, which are Fred/Snape/George, and in which they end up with an insanely large number of children), and there's also "Infinite Consequences", which is Lionel/Lex (non-con warning -- poor Lex!) and "Paradigm Shift", its Clex sequel, which is still a WiP.