What abandoned plot lines you'd like to have seen?

A few plot lines were dropped before being developed. To mention a few that comes to mind:

- Olivia having a drinking problem;
- Amaro being a dirty cop;
- Carisi's boss being introduced in the end of season 25 hinting some sort of feud with SVU team.

I'm sure there are more. What is something hinted that you would liked to have seen?