First off, perhaps a Moderator could move this to background or general discussion? I think it's more apropos.
I'm with you on your train of thought. Here's what I've been working on:
I returned to
40k after about 19 years and have the mini's to field a full army of Space Marines(infantry only), but can't abide the thought of fighting other Imperium Forces.
I started in the Rogue Trader days, when marines weren't as fleshed out. They wrote things like "kil kil kil" and "Lust for blud" on their affects.
I started anew with orks because I'm trying to perfect my own chapter as well.
I've gone with a similar idea for Blood Angels, because I love the codex, but have slowly come to appreciate the vanilla Codex as very potent as well.
Subsequently, I want a Chapter that fights for the Imperium, but has the storyline background to excuse fighting Imperial forces, and allows me to use the Blood Angel or Vanilla Codex, so not a known chapter. My result is something similar to the Knights of Blood.....at least......a renegade chapter!
Even better, I've fleshed it out even more.
Enter: Ordo Liberatus. An Ordo of the Inquisition that focuses on the worlds still needing to be brought back within the folds of the Imperium. There are still thousands of them between the worlds recorded and participating. The Ordo faces all forms of heresy, from the domestic of heretics, corruption of chaos, the arrogant and obstinate, unsanctioned psykers and witches, to the supernatural of daemons, to the alien xenos. All these influences must be dealt with, and while the Ordo cannot claim any such level of supreme specialization as those of Hereticus, Malleus, or Xenos, deal with them it must, and thus needed its own military arm.
Enter: Angels Ascendant. Created in a later founding using the Gene-Seed of the Blood Angels and Dark Angels Primarchs, it was an attempt to temper the rage of the Blood Angels with the restraint and humility of the Dark Angels. It failed.
As a militant arm of the Ordo Liberatus, the Angels Ascendant is a crusade fleet. Currently, there is no home-world, as I see they have everything mobile, though they do keep some recruitment worlds. As necessary, the Codex is only loosely followed, and the chapter numbers well over 1000. There are several crusade fleets, some with dominant traits of Blood Angels or Dark Angels, with the most well balanced using the vanilla Codex.
In several occasions of liberating planets, the Ascendants have succumbed to the black rage and subsequently slaughtered massive amounts of the populace. Though much of this never reaches the Lords of Terra, on occasion a complaint does.
When asked to answer for this, it is met with haughtiness and contempt from both Chapter and Crusade masters, and Inquisitors of the Ordo, claiming that what must be done is done.
There is much controversy over the chapter back on Terra. They do not report directly to the lords, and the Ordo retains its own counsel. This is balanced by the fact that new worlds and tithes enrich the coffers of the Imperium.
At one point, the chapter is declared renegade, and refuses to return. Occasionally, a chapter is sent after them, or there are clashes with the
IG or even
SoB. Most lords look the other way because of the increase of land and income, but others still pursue the return and disbanding(eradication) of the chapter.
So here we have some history. I've been stuck on color scheme. I wanted to incorporate red, because in every successor chapter of the Blood Angels, minus Lamenters, it is dominant. I thought halved Black and Red, but the Angels Sanguine do that. Then I thought, red and green, but don't want them called "Christmas Marines". I'm thinking of halving them, lower black, and upper white, to incorporate the "ascending" part.....out of darkness. This was originally a color scheme for a gag chapter I was working on. The Chapter of Latter Day Primarchs......known for its heavy use of bikes. I didn't want to cross white and red(halved or quartered) because they'd all look like medics. So far, I'm almost 90% set on white over black. Thoought about going white with a silver left arm, opposite of Deathwatch.
Also considered it a chapter similar to deathwatch, with the Angels Ascendant universally joining to avoid persecution.
I REALLY wanted to make a Deathwatch army, but they'd almost exclusively fight xenos, to be proper.
Ah well, there's some brainstorming from someone else, hope it helps a bit