Looks like they are getting on just fine, there's no way Chilli would have been that relaxed and close to Dave on week 2 let alone day 2!
With his collar, he does seem a little young and small for one and with him being indoors not entirely necessary. Also, is it a safety collar? He could easily get it caught on something and if it doesn't release, well, you can imagine potential outcomes. Not having a go, just want to make sure he's as happy as he looks!