There's a guide listing the best choices for each route.
Anders's is:
Sit here with Anders, Take umbrella, Don't get any funny ideas.
Disagree, Get some veggies, Change the topic, Can I see your rocks, too? Ask what's going on, Map: Bublix, Ask him to help you shop.
I'd consider it. Go visit Anders, Dialogue, Woke up early, bleh.
It's...I don't know, Dialogue, Nothing in particular, I'm worried.
Tell him you think you saw Anders, Map: Arcade, Dialogue
Pretzel with spices, Dialogue, Sure!, Future Funk song, Dialogue
Dialogue, Dialogue, Focus on Lars, Praise Anders, Sit next to Anders, Look to Anders, Help Anders yourself, Ask Coach Gil to stop, Dialogue, I'll stay here
Ask him to draw something to commemorate the trip, Dialogue
Promise to work through whatever happens, Listen in, Enjoy companionable silence, Ask Anders if he likes being busy
Intimidate him, Dialogue