Thank you, everyone. It's been a week, and Talon is doing really great. He walked out from the clinic and was totally himself, being a bit groggy aside… Little scar heals up nicely. His behavior is very good, and he plays with his sister like a rascal that he is.
Kasiya was already spayed when I got her, so I did not experience going through the neutering with her - although judging by the scar it is definitely far more complicated procedure. I hear stitches come out 10 days post-surgery. Poor baby girl! But of course she is totally fine now.
In any case, your support was very important to me and hearing "he'll be fine" was exactly what I needed - and he, indeed, is fine! Thanks again, all!