If Cas learned this kind of love from Jimmy [powerful family love] it makes sense. And I personally think Dean taught him a different love, unintentional on Dean's part. I mean Cas cared deeply about his angelic family too.
Faustian Date >>>I don't even know these characters but I ship them already. *yaoi moment:* ~get him pregnant!~ // ive kinda gotten really invested in these characters even if you never really get to know much about them