The antihero goes through immoral actions and try to justify their actions with a higher purpose. Both dark, exciting and bloody.
Both movies centers around a teacher and his/hers relationship with a student. Both are very dark and has many twists.
Both of the series are written by the same screenwriter, the tone follows through all of his/her work so It's a big chance that you'll enjoy Save Me if you liked Strangers From Hell. Both works circles around a group of people that gets isolated from the rest of society and develops insane behaviors because of it, very gruesome.