Fed them in the room together again. Had a weird moment when they ran to the door puffed up. I think they ended up being together for around 4 hours with a break in the middle to cool down.
0:00 Eating
5:22 Puffed up running to the door
6:43 Checking in on the cats
12:29 Smokey guarding the door and goop stick
19:16 Onyx guarding the door and then back to his room
...
https://www.youtube.com/watch?v=THiSQUq1SQE