This is a pretty unlikely pairing.

One is a genius, the other's a 9

One is a genius, the other's a nurse/archer.

One is a genius, the other's even more genius.

Smart and smarter

Nicklance said:
One is a genius, the other's a 9

Cirno, are you pondering what I'm pondering?

Fuantei did this before there were.... casualties

narocroc said:
Cirno, are you pondering what I'm pondering?

"I think so, Eirin, but won't it go straight to my hips?!"

narocroc said:
Cirno, are you pondering what I'm pondering?

"I think so, Eirin, but where are we going to find a duck and a hose at this hour?"

narocroc said:
Cirno, are you pondering what I'm pondering?

"I think so, Eirin, but could old ladies still can wear string bikinis?"

narocroc said:
Cirno, are you pondering what I'm pondering?

"I think so, Eirin, but what if she won't give us her liver?"

It's Cirno and the Brain
Yes, Cirno and the Brain
One is a genius,
the other's inane!
They are pictured here
though the reason is unclear
Who knows?
They're Cirno and the Brain, Brain, Brain, Brain
Brain, Brain, Brain, Brain
Brain.

Before each night is done
Just for you and me
By the coming of the next game
Main characters they'll be!

They're Cirno and the Brain
Yes, Cirno and the Brain
Their eternal campaign
Is easy to explain!
To prove their character worth
A new game they shall birth!
Who knows?
They're Cirno and the Brain, Brain, Brain, Brain
Brain, Brain, Brain, Brain
Atai!

windfalcon, you win a copious amount of internets.

Brain of the Moon & Brain of the Earth