Being a nani operator Felli has trouble with emotions. This is due to the large amount of information going into their brains at any given time, there is so much information that they can't process and react to it all as it comes in therefore nani operators shut off their emotions. As a result nani operators have trouble expressing any form of emotion. This also allows Felli to keep a cool head and an aloof cold stair both in and ouside of battle. However Felli doesn't seem to have any trouble expressing anger and jealousy especially when it comes to Layfon Alseif to whom she apparently has strong romantic feelings for despite her near constant physical and verbal abuse towards him. She usually leaves Layfon or anyone who angers in horrible pain as she is seen exhibiting super-human strength when she is angry (most notably Layfon and Kalian). Her crush on layfon along with Nina Antalk, Mayshen, and Lyrin Marfes which sometimes leads to conflicts between the girls or more commonly with Layfon or one of the girls getting hurt ( Layfon physically, the girls emotionally. Because of her inability to express emotion it is very rare to see her smile, so rare in fact that Sharnid Elipton (the sniper of the 17th platoon) spied on her at her work place in hopes of catching a picture of her smiling beacause "She's so popular with all of the guys that if I got a picture of her smiling I could sell it for a wad of cash". At the end of the episode Layfon actually does succeeds in making her smile to which she responds by stabbing him with her heel and walking away. Other than when it comes to Layfon Felli is usually quite distant as she is often seen watching, reading a book, or somewhere else while the rest of the platoon is socializing. She seems to harbor a great amount resent her brother Kalian Loss for forcing her to join military when she wanted to find and follow her own path. Even now she strives to find her own path and thanks to Layfon she has started to take steps to find it something kalian finds noteworthy.
Felli is short girl with a very petite build and pale skin. Her long silver hair falls down to her knees with two strands elevated slightly on either side of her head, several strands that frame her face and bangs that fall in front her face right between her grey eyes. Felli is most often seen in her uniform, an off-white jacket with blue cuffs, shoulders, and lapel with gold trim and a red tie. Felli's skirt has a white frill underneath. She has also been seen working at a cafe in both a frilly pink maid outfit, which the owner decided did not suit her due to her aloof expression, and a black maid outfit. Felli is considered very attractive as Sharnid mentioned that she popular with the boys. Felli rarely shows much in the way of emotion and as such usually holds a rather blank expression on her face, aside from when someone makes her angry. Though she has been known to smile, it happens so rarely that Sharnid believes a picture of her smile would fetch a hefty sum.
From the beginning, Felli has felt a sort of kinship to Layfon as both were forced to join the military arts department by her brother Kalian. Layfon is also one of the few that has seen Felli smile, though she did drive her heel into his shin for seeing it. As the series progresses, Felli develops a rather obvious crush on Layfon, to the point of making excuses during swimming lesson simply so she can continue to hold his hand. Layfon himself shows Felli the utmost respect, both as his senior at the academy and as his friend. Despite the rather significant amount of time the two spend together, Layfon remains oblivious to her feelings for him. However, these feelings never seem to stop her from puching or kicking him when he does or says something stupid.
Kalian is Felli's older brother and president of the student council. Felli holds great disdain towards her brother because he forced her into the military arts rather than allowing her to find her own path in life. As such, Kalian is one of the most frequent victims of Felli's abuse, once kicking him with such force that she snapped his leg bone. Despite her cold and abusive treatment towards him, Kalian does show genuine affection for Felli, albeit in his own strange way. He even abducted Layfon during a their trip to the spa and threatened him when he thought he was trying to make a move on Felli.
Nina is easily Felli's closest friend and vice versa. The girls are rather close to one another and often act like sisters more than a squad leader and her subordinate. Nina shows great concern for Felli when she was attacked in episode 4, and relief upon seeing her unharmed. Felli also does not seem to mind physical contact with Nina, making no attempt to resist when the latter hugged her and examined her for wounds, though the sudden embrace did seem to surprise Felli somewhat. Nina is also one of the few people that gets to see Felli smile, as she makes no attempt to hide it when with Nina as seen during their trip to the spa. Their closeness does not stop them from argueing over who gets to help Layfon and Mayshen cook, though this came off more as a playful spat than an actual arguement.