In Bleach, the shonen hero Ichigo Kurosaki gains Soul Reaper powers from Rukia Kuchiki, then begins his career as a substitute Soul Reaper, fighting villains of all shapes and sizes. Some enemies become allies, with Uryu Ishida being an example, and Nelliel Tu Odelschwank being another. In fact, Nelliel never wished Ichigo any harm at all, despite being an Arrancar.
Nelliel was once among the ten mighty Espadas, until she was betrayed by Nnoitora Gilga and badly injured. She met Ichigo during the mission to rescue Orihime Inoue, and Nelliel became Ichigo's loyal friend and ally at once. But there is more to this quirky Arrancar than meets the eye, and Nelliel certainly has a few secrets that Ichigo gradually learned one by one.
10 She Likes To Read
This is a rather obscure part of Nelliel's character, and Ichigo probably never saw this side of her. At one point during the recent past, Nelliel had just defeated Nnoitora in yet another sparring match, and she actually knocked him out. When Nnoitora came to, he saw Nelliel sitting down, reading a small paperback book.
Where Nelliel found that book is anyone's guess, but it's intriguing to see an Arrancar have a hobby aside from fighting and killing. It ties into Nelliel's theme of being a patient, kind and sensitive person.
9 She's Like A Knight
In more than one way, Nelliel is like a noble knight. Many anime and manga franchises like the idea of a noble European style knight, often a gentleman with fair hair and a dazzling smile. But in all the ways that count, Nelliel is like that, too, even if she lacks actual shining armor.
Nelliel doesn't fight for fun or to fuel a grudge, like Nnoitora and Grimmjow Jaegerjaques do. Instead, she will only draw her sword if there is a good reason to fight, such as self-defense or shielding the innocent from bullies. She needs purpose and justice in combat, not just glory.
8 She's Like Izuru Kira & Shuhei Hisagi
Nelliel has a balanced view on violence and power, and that makes her similar to the Soul Reapers, rather than like her fellow Arrancars. For example, Izuru Kira of squad 3 and Shuhei Hisagi of squad 9 also have equal respect and fear of their own power.
Like Izuru and Shuhei, Nelliel is mature enough and insightful enough to realize that combat is a grim and monstrous thing, and warriors must respect their own power and their opponents, or they'll get lost in bloodlust and carnage. Nelliel sees combat for what it is, not for what she can get out of it.
7 To Her, Action Speaks Louder Than Words
On a somewhat related note, Nelliel isn't impressed with bold declarations of power or taunts, and she especially doesn't like the idea of someone flaunting their power or brandishing their weapon to intimidate others or send a message.
Nelliel will scold her enemies and correct them on their faulty worldviews, but that's not the same as taunting or mocking them, and she can't stand Nnoitora's boastful personality. To her, true warriors are those who demonstrate their power when the time is right, and words are merely that: words.
6 Her Hair Color Changes
This is a minor detail, and it's an example of how the animation studio either misses small details or makes small aesthetic changes to match personal taste. In the original Bleach manga, Nelliel had fair green hair on the colored pages, but that changed in the anime later on.
Nelliel's hair became turquoise, a slightly darker color with some blue added. Perhaps the animators felt that this color better matched Nelliel's personality, or maybe it was so her hair was easier to tell apart from her ragged green clothing.
5 Her Time Limit To Stay In Her Adult Form
When Nelliel was a regular Arrancar and an Espada, she didn't have any complications or issues with her powers or body. But after Nnoitora badly injured her head, Nelliel shrank into a child, and her energy leaked right out of her cranium.
Now, Nelliel can resume her adult form in case of emergency, but she can't keep it up for long. She wears out and reverts to her child form before long, but later on, Kisuke Urahara gave her an armband that would keep her in adult form, fortunately for her fellow heroes.
4 She's Generous
Overall, Nelliel is a noble and gentle person, and that sets her apart from Arrancars like Barragan Luisenbarn and Grimmjow. Not only is she humble about her own power in combat, but she is also gracious with other people, and she demands very little from them.
Despite her intense distaste for Nnoitora, Nelliel never wanted to kill him, even when Nnoitora bullied Ichigo and Orihime during the Hueco Mundo story arc. She was also eager to repay Ichigo for all he had done for her up to this point, showing a strong sense of fairness.
3 Her Memories Don't Go Both Ways
Nelliel can switch back and forth between her toddler and adult bodies, but not always by will. It should also be noted that her memories are inconsistent when transforming like this, based on her dialogue and her actions.
Nelliel's child form only remembers things from that child form; she doesn't remember anything from her adult Espada life. But when Nelliel turned back into an adult, she clearly recalled everything that Ichigo had done for her while she was in toddler form. Only her adult form has all memories of both forms.
2 She Represents Aikido
In real life, aikido is a martial arts technique that emphasizes gentleness and turning the enemy's energy on themselves, rather than creating an actual attack. In a way, aikido is about diverting the opponent's energy to make sure no one gets badly hurt (there's much more to it than that, of course).
In a way, Nelliel embodies aikido with her ability to eat cero blasts. In her toddler form, Nelliel can absorb an enemy's cero blast, contain it in her mouth, then fire it right back, without needing to fire her own. In her adult form, she can redirect a cero blast and add her own, creating a more aggressive technique. The enemy's energy becomes their downfall.
1 Her Mask Keeps Changing
Nelliel's Hollow mask remains take four different forms in the story, based on a few factors. Her original mask remains were like a ram skull atop her head, complete with upper teeth and curling horns. Then she became a toddler, and her mask became much simpler, even cartoony. It was also missing its left teeth.
Once Nelliel regained her adult form, her original mask was mostly restored, but it was still missing its left teeth, a reminder of Nnoitora's treacherous ambush. When Nelliel released her zanpakuto, her skull changed yet again, with the horns being less curvy. However, the left teeth were still missing. Overall, Nelliel's mask takes four different forms in the story.