For lack of a better term , I would say he's a bit eccentric.

She has an eye for beauty.

I'll be away for a bit.

I have a passion for foreign languages.

The game turned into a free-for-all as everyone started playing without any rules.

There are many fora where people can discuss various topics.

He is a good-for-nothing person.

For some reason, I couldn't sleep last night.

I am studying for the purpose of passing the exam.

I wanted a promotion, but I had to settle for a pay raise instead.