Tengens wives are basically Senjuros moms. Since his mom died too young for him to know her, he didnt have much female influence in his life. But, when Rengoku met Tengen and they bacame good friends Senjuro also got to meet Tengen. And, he would have been maybe 12-13 (but because hes so...shelterd and severely traumatized hes like...probs behind a few years in most categories) and probably fairly shy. However, when he met Tengens wives he literally just attached himself to them. And, whenever Tengen and Rengoku wasnted to hang out, or when stuff was going on with Shinjuro he would tag along and get to see Tengens wives.
They have had many sleepovers and they all adore Senjuros and snuggle and play games and all that. Its important to have strong positive women in your life, and, Tengens wives are that for Senjuro. And since Tengen is now retired and has a baby, that means Senjuro gets to see the baby and he can help out whenever the others need a little break :)
