40 hours later of couch co-op with my inexperienced partner who chose Wizard for some reason, and their character is finally useful in battle near the end of act 2.

I try not to control them, I just say what I'm doing and planning so they don't launch my team off a cliff. Occasionally I'll say "Yes, counterspell cloudkill please." but I'm mostly hands off. When asked for advice I give it, I'm not a monster, I just think if we're playing together we should both get to play.

I haven't played any DnD since 3rd, and my partner loves these role playing shows like Critical Role or whatever. My biggest takeaway I've had from our sessions is that those shows most not have any mechanics whatsoever.