Pairing is very much a cultural thing. It's either normal or it's not. If it's not it tends to only be a "ask me for help if needed", which leads to not doing it. That's not really pairing either, that's just "Let me know if anybody needs any help."

The perks of pairing are regularly unsticking stuck people, getting another set of eyes on a problem, learning from each others development habits as a side effect of doing your job. People tend to really overthink what is involved in pairing, turning it into some rigidly drilled type of exercise.

All that is needed to get most of the benefits is to fire up a screen share and verbally communicate while the main developer keeps working. Everything else falls into place. Even if it's just for a couple of hours here and there rather than "finish this entire story with this person" it's beneficial.

When people get stuck on something, it can become harder for them to focus. They'll start looking for alternatives like opening HN or Facebook, reading an article, etc. For a lot of people trying to prove themselves, asking for help isn't going to happen until it's too late and that makes it easy for people to work in their own little bubble.

If it's considered an interruption for you to screen share while the person continues to code, you're doing pairing wrong.