You keep taking this personally, and I can only remind you that this is a game so many times.
That is the problem with #lurias . If you want your character to betray someone you'll almost be forced to lie OoC. That is why whenever it happens it's as a result of, or results in, OoC fights. The IC/OoC separation is so thin, way too clanish-like.
Now, if you are not in the channel (or in the several more private ones) you have little chances in politics, except as a pawn.
The Blood Debt is actually a fairly recent creation. Malus came up with it as a reason to get rid of some of his enemies.
It has definitely not been in place for that long as my character was there for a very long time.
This is an entirely Solarian invention, not Lurian at all. And when Tybalt tried to duel people he was mostly laughed at. I really doubt Sevastian will meet a very different response.