Two stories here:
1. Justin is with Ethan. Ethan cooks for Justin and intentionally gives him food poisoning with spoiled food. That's really all I recall from this one, although I assume Brian comes in and rescues Justin.
2. Again, Justin is with Ethan and is in the hospital. Brian, however, still has Justin's POA. In fact, they are actually still together and Brian was just letting Justin spread his wings and experience other kinds of relationships before they fully settled down. Ethan finds out at the hospital that he was just a kind of 'time out' for Justin, and Justin has always been Brian's partner.
Any help on these is greatly appreciated. I'm going to go and search the tags, again, in case I missed them, but I didn't see anything that jumped out at me.
1: Transitions by Randall Morgan. Link in comments. Found by the wonderful deviant_queen
2: Power of Attorney by Twinkminded. Can be found on Midnight Whispers. Found by the speedy and amazing cuivresdesaxe
Thanks to everyone. My weekend was much better with those reads!