gryffindors are loyal to the righteous.
courage runs in their blood, but more importantly, gryffindors often find themselves siding with the one who wields courage themselves. be it a knightly hero or an unassuming underdog, gryffindors are passionate and spirited about their alignment, but this spirit can enter them into situations they have yet to prepare for.

ravenclaws are loyal to the correct.
as the ones who always want a triumph of the truth, ravenclaws are most likely to assess the facts, analyze the opinions, and only then align themselves with who they think to be the correct party. however, not all ravenclaws share the same "correct" mindset, and they will often debate and differ as to who should be making the decisions.

hufflepuffs are loyal to the good.
by nature, hufflepuffs want for virtue and morality. even if the position they take isn't necessarily the one with the highest odds, they will always side that resides closest with their moral beliefs. when it comes down to it, true hufflepuffs will always fight for integrity of purpose. this does mean that sometimes they will sacrifice themselves for the greater good.

slytherins are loyal to the worthy.
a slytherin knows that loyalty is not something to be handed out thoughtlessly. to obtain a slytherin's allegiance, you must prove your cause to be within their interest. often, their loyalty lies with blood or close friends, as they tend to rely on the ones they trust during times of trouble. in doing so, however, they can lose their morality in fear of losing a loved one's life - or their own.