Helynna Valeria

Inquisitor Helynna Valeria was an Ordo Xenos radical and a recurring background character. Despite never appearing on the tabletop or any novels, she had a surprisingly well developed story, told through the various codices that she kept popping up in.

Being a radical, Valeria was of the bent that no tool and no scrap of knowledge originating from the material plane shouldn't be in the Imperium's quiver (she stopped short of Chaos artifacts, but again she was an Ordo Xenos radical, not one from the Ordo Malleus). She lead many expeditions for acquisitions and fact finding missions. One of her more famous missions was successfully retrieving a xenos artifact called the Dimensional Forge, a device capable of creating a lightyears-wide null zone, an area where daemons can't get in (and should probably also keep ships from transitioning to realspace and block psychic powers, but hey, that never stopped a plot convenience or three). Unfortunately the Dimensional Forge was lost when the Black Templars killed a xenos psyker and its psychic death scream crippled much of nearby Imperial space.

Valeria had to retrack the device, and found it on a nearby hiveworld which was under attack by daemons. As she fought to recover the device, she was tracked down by Inquisitor Emil Darkhammer, an old rival. Darkhammer was a fellow Ordo Xenos Inquisitor, but where Valeria was a radical who was convinced that nothing was out of Imperial servants' sanctimonious hands, Darkhammer was a Monodominant Puritan. In other words, he was Valeria's opposite: a firm and strident believer that if it didn't come from Emperor and Imperium, it should be burnt down. Being Valeria's bitter rival, a colossal asshole, and the kind of Exteriminatus-happy bastard that was the reason the Ordo Excorium was founded to keep control of, Darkhammer condemned the world and its billions of survivors to Exterminatus under the pretense of keeping the daemons from spreading, but was really just to burn down whatever Valeria was trying to get back. Whether this was out of spite or a misguided attempt to protect the Imperium from radicals like Valeria is currently unknown, but since Darkhammer is known to drop an Exterminatus to eliminate single tainted artifacts, it doesn't leave room for a charitable interpretation either way. Valeria managed to escape, declared Darkhammer to be a double heretic, and had spent a lot of time hunting him down since. The rest of the Inquisition has been happy to just sit back and watch things unfold of their own accord, since taking sides would mean everybody would start doing it, and a bigger and an even more pointless conflict would ensue.

Another one of her more notable expeditions was taking a bunch of Catachans to the world of Solemence to see why the Tyranids were going way, way out of their way to stay the hell away. The same Solemence which happens to be the home of a certain Phaeron named Trazyn. After the hijinks there, Trazyn thanked Inquisitor Valeria by sending her a gift of an armed Tesseract Labyrinth. Really. Maybe. Depending on how much sarcasm you read into the accompanying letter. Valeria actually managed to disarm the damned thing, and kept it. Out of respect, Trazyn let her keep it and even became a penpal to Valeria.

Inquisitor Valeria would later get BLAMMED! for consorting with xenos. However, when Gathering Storm rolled out, circumstances around her death were slightly retconned and expanded. It was made so that Trazyn to have decided to keep such a clever monkey around, but keeping her on a leash in the form of mindshackle scarabs. She was outed and killed by Inquisitor Greyfax, who wasn't going to be tolerating a compromised Inquisitor in the ranks. Oddly, however, the game Battlefleet Gothic: Armada II claims that Darkhammer was involved in Valeria's death, somehow.