i second that.
Ryuuji definitely hates being abused, even though he more or less have to, because i understand how imperfect people have to double the effort in order to get friends , and this is certainly in the case of Ryujii. afterall, even though people knows that he isnt really a delinquent, he only has a small group of real friends.
noto and haruta? they only seem like abusing Ryuji for me (using ryuji to skip afterclass cleaning, using ryuji to "fill-in-numbers" to meet girls. i dont think them as real friends really.
masochists are something like this
http://www.onemanga.com/Zero_no_Tsukaima/12/30/
and ryuji does nothing of that sort definitely