Tobirama always says that he prefers peace and quiet, that he does his best work when Hashirama is away on missions or training on the other side of the Senju compound, and not subjecting him to loud mood swings and mental whiplash. So Father built him a lab on the outskirts of the compound, where he could slap up some noise-dampening seals and have as much quiet as he likes.

Hashirama has always suspected Tobirama wasn't telling the whole truth, and as the lab blows up for the fifth time in two days, his otouto staggering out covered in ash and slightly singed, muttering manically under his breath, he feels himself proven right.