skinny chives - how to fatten them up

[Dozeynoo]

I have some chives in a pot but they look very skinny. I grew them from seed about 3 years ago and they have been somewhat neglected since due to the arrival of ds1 & ds2.

Do they like sun or shade? Dry or Wet? Heavy or light soil?

Thanks.

Chives are thin though. I mean, just how skinny are we talking here?