save for the end

Alec goes to help Magnus heal Luke, unbeknownst to either of them Magnus ends up in heat. The next thing either of them knows both are in bed, Alec knotting and biting Magnus as his. The next morning Alec wakes up terrified of what he did, because being a Shadowhunter means he isn't allowed to court men, let alone a Downworlder. So leaves without talking to Magnus.Magnus shows up months later to reinforce the wards of the Institute and Alec finds out that Magnus is pregnant. With his child. Alec wants to protect to Magnus, who is still angry. Unknown to them someone is after Magnus and his unborn child.