User blog comment:B214/Volume 17 spoilers./@comment-117.193.177.20-20140221052531/@comment-24468758-20140221072136

Rossweisse is a pitiful but still very young version of Grayfia:

outward appearance, low alcohol tolerance, take care of finances (with Ross overdoing it), both love a person who represents "crimson" (sorry Euclide "red" is not enough), serious personality, both fell in love during a "war" (many larger battles between two factions should already count as war), both are able to explain something for the rather dumb Issei to understand (which in not a small feat).

That is everything I can think of at the moment.