Today I want to talk about Serina's hair. The wiki only has Serina's red cross outfit as a chibi, so if anyone can find a non-chibi version of that I'll analyze it too.
Serina has short, pink mostly hair that goes down to her neck. Mostly because she has a single feather that seems to be an extension of her hair, which is on her left side and goes down to her chest. Because of this, she's a bit like Suzumi, though more subtle, in the one-winged angel hairstyle. It definitely fits her, because nobody would notice it at a glance, fitting into her character of appearing whenever needed. She wears the left side of her hair in a little pigtail with a pink ribbon, and has what seems to be a hairband with the remedial knight's logo on it. It's a simple hairstyle, but it does a good job at showing Serina's sweetness.
Her Christmas outfit takes an interesting trind- because of her beret having a cross ribbon on it, she instead tied her hair into a hairbun on her right side. She seems to care a lot about the rest of her hair, but her bangs are typically kept static. Perhaps her feather hair is very sensitive? It would explain why her hair is typically tied up, so she doesn't brush against it and cause an imbalance.
Her nurse outfit is an oxymoron- she's one of the school nurses in Trinity, but she has decided to ditch the nurse outfit for... A nurse outfit. It's a unique way to show her as a compassionate individual who cares about others, that's for sure. And yes, her hair with her nurse outfit is different from her hair with her nurse outfit. The most obvious example of this is with her ribbon being tied different, but her bangs are now swept left instead of right. Her feather is also more predominantly shown, though with her outfit being the same color, it might be hard to spot. Her hairband is also simpler, too, likely meant to be seen as a more generic nurse symbol as opposed to the normal hairband which tells you that this is a girl from Trinity. She is very eager to help people take their medications!
Serina's an odd one. She has simple hair, yet she shows a lot of personality with it. She steps light as a feather, and her pink shows a unique, wholesome and bright compassion that helps balance Mine's unique personality. If I were to equate the Remedial Knights to specific medical practices, she seems to be like patient comfort, while Mine is effective results and Hanae is a positive attitude. It's a pretty good juxtaposition to Sena, who is a triage specialist and takes that attitude with her everywhere. I imagine that Serina is very popular with kids as a result of her simple yet kind personality allowing both the timid and the jolly to open up to her.
How her hair smells... It definitely smells like something, going by how she likes Samuela "The Beyond", which interestingly doesn't carry over to her Christmas alt! I think that she wears Samuela not just to smell good, but also to smell capable and familiar. If your doctor can treat you while wearing such a renowned perfume, she'll probably endear you by virtue of smelling competent. I think her hair would work to complement her choice in perfume, smelling like a bouquet that comes with a "Get Well Soon!" card.