Captain of the 13th Division
Siegfried Bieber is a quiet man who enjoys chess, is learning the rules to shogi, and can often be seen reading outdoors when not on a mission. He is growing very skilled at Shunpo, and has achieved near-mastery of Hakudo.
His demeanor in combat is usually very serious, and either frightened, determined, or annoyed, depending on how the fight is going. He is not averse to dirty fighting when the opportunity presents itself, believing that fair fights are for those who have nothing worth protecting.
He was close to Kayzumai Yen, and seriously affected by his death.
Since calling out former Captain Girikio and assuming his former position, Siegfried has gained a great deal of confidence in his abilities, along with substantially greater mastery of them. He commands his Division as best he can, and has come to understand what he's been fighting for. He values the lives of innocent mortals and his subordinates over almost anything else, and will put himself through anything to protect any one of them.
He's coming to terms with the idea that Arrancar are people, just like anyone else, an idea that was almost unthinkable to him in the past, through a combination of Mia, Kayi, and Isara.
Appearance
Wears a normal kimono, save for a buckled belt with his name and former rank (Vice Captain) embroidered on it. His footwear is also a bit odd, using Roman-style sandals instead of the traditional geta whenever possible. His black hair typically is a mess of the "bed-head" variety. Now that he is Captain, he also wears the burnt, battered haori of 13th Division, and has vowed not to cease wearing it until he's made up for its bad karma.
His eyes have gotten a bit more open in his time as Captain, to becoming simply hooded, letting those who have worked with him find out for the first time that his eyes are green.
He has a somewhat heavier build than the average Japanese man, and is in top physical condition.
General Abilities
Siegfried is a master of Hakudo, and proficient with whips. His flash steps capacity is nearly limitless, and his speed within them is on the higher end of Captain capacity. He is able to read the general intentions of those who are sufficiently akin to normal humans or Hollows from their body language, and possesses the ability to throw his voice. His Kido is not outstanding, though he can perform up to Hado 63 (Raikoho), inefficiently and with incantation. His repertoire without incantation is limited to most bakudo below thirty, and Hado up to Shakkaho. He has recently been trained in the art of Shunko, and though he has not mastered it yet, he's getting reasonably close.
Zanpaktou, Ingakumo (Fate Spider)
Sealed form: a sword breaker
Shikai, "Oridase, Ingakumo!" (Weave, Fate Spider!)
The sword breaker rapidly covers itself and Bieber's right forearm with what appears to be spider silk. A single strand of the stuff extends from the tip of the blade, long enough to serve as a whip.
This spider silk is extremely concentrated spirit energy, drawn from the wielder. As such, it is considerably stronger than most substances, allowing parrying with the spiderweb gauntlet. More importantly, the single strand extending from the tip serves much like a monomolecular blade, able to slice through pretty much anything.
First Shikai special ability (unnamed, as it is not strictly an attack): Siegfried can spend more of his spiritual energy to extend the blade. He can extend the range to roughly twice the length of a bullwhip, but is not skilled enough to do it in the middle of a slice. It can be used to extend the gauntlet as well, but it takes a while when not concentrating too heavily on it.
Kumo no Soshaku (Spider's Bite): Siegfried can consume all of the spiritsilk on his arm and blade (severing his connection to the whip in the process) to deliver a single, extremely enhanced punch. Striking force is roughly equivalent to direct contact with an exploding grenade.
Bankai, "Yokuyokuna Ingakumo" (Careful Fate Spider)
A quick burst of reiatsu first billows from Siegfried, then collapses back in, quite possibly pulling things with low momentum to him. His body is now covered in spiritsilk armor, and his face is covered by a spiritsilk ski mask. His zanpaktou's sealed form remains in his right hand, now with only a binding around its handle to prevent disarming.
This form presents him with dramatically improved resilience, as well as the ability to create nearly infinite whips from any point on his body, though the range can only be improved at the cost of much greater windup time. Furthermore, his spiritsilk now has the special ability of numbing (within the space of one post) and then completely paralyzing (within the space of two) any body part in which he can strike a bleeding wound. This does not work with his whips, as they move too quickly to transfer an adequate dose of poison.
Lastly, he can now perform Kumo no Soshaku with any part of his body, or multiple parts at once. This is more useful in bankai, as he can use his reiatsu to seal cuts in his armor, and even regrow parts of it from scratch, up to a total of two extra sets of armor.
Revealed Bankai Techniques
Spider Jet: A technique which uses the explosive capacity of Kumo no Soshaku for propulsion, allowing him to reach speeds matched only by the true speed demons of the Seireitei.
Radiant Spider Armor: Using extremely small-scale Kumo no Soshaku to send tiny whips into the air, Siegfried can create a field of blades which has easily cut through immense blocks of stone without any further effort on his part.
Spirit
Ingakumo appears as a large spider, which communicates telepathically. It is somewhat reserved, like its master, but can be sociable enough. If Siegfried goes too long without training to understand it, Ingakumo will start to nag him.
Inner World
Siegfried has yet to need to confront his Inner Hollow, instead simply confronting his own moral failings. Thus, he has never seen his Inner World. However, it is an immense web, with everything he's ever done, thought, or experienced connected to and supported by one another.