(All the date ideas put in here are dates I think sero would plan and dates I would personally like to go on, so I'm sorry if this doesn't fit your personal preference.)

Sero, in my perspective, is a very chill person. He's going to be the dad friend in a group. He notices things not everyone will and takes note of them.

If you were dating Sero, he would pick up on some of your little traits that usually get hidden underneath other things. He would take those small traits and interests and form a date around them.

He would take you on dates in the middle of the woods, with string lights hangin from the trees, lanterns holding down a blanket for a picnic. Maybe it's 2am, maybe it's 7am. He based the time on your sleep schedule. He has either your favorite dinner food and desserts, or your favorite breakfast food and desserts.

He would take you to a cave on a beach with a projector and watch a movie there. A think blanket to sit on and some drinks in a cooler. Just watching a movie in a cave at the beach.

In short, he would take the smaller, not so noticeable parts of your personality and make you feel special.