The normal way. Flirting, talking, dating.

As long as someone is addressing their depression (e.g. therapy or whatever) and not expecting a relationship to fix it then it is fine and healthy to join one.

Granted loneliness can definitely cause depression, so an exceptional case there.

In terms of dark room vs. extrovert, i can speak from experience that both can feel lonely and the depressive episodes still come and go. IMO better to have higher highs because you’re getting the lows either way 🤷.