“No! It's just that... I collapse into a coma when I get too hungry! That's why I've got to accept everyone's generous food offers.”
—Ilyana in a support conversation with Zihark
Prior to the events of Path of Radiance, Ilyana had been traveling with a merchant caravan, but was separated from it during a Daein invasion. She is then forced into helping the Daein forces fight the mercenaries. When she meets Ike during the ensuing battle, she learns that the mercenaries are guarding the caravan, whereupon she opts to defect to him. Ilyana will then remain with the Greil Mercenaries until the Mad King Ashnard is defeated.
A few years later in Radiant Dawn, Ilyana joins the Dawn Brigade after Micaiah rescues her and Aimee from a Daein prison. She will then assist Micaiah in her quest to liberate Daein from Begnion's rule. Ilyana later joins Ike's group in Part III when her merchant convoy arrives in Begnion. After the war, Ilyana will continue to travel around the continent of Tellius with the merchant convoy.
Ilyana's most noticeable trait comes in the form of her unusually voracious metabolism. This often causes her to remain ravenous no matter how much she eats, to the point that she may even be on the verge of collapse, despite having consumed large meals. Ilyana makes a mental note to remember Heather, Zihark, and Gatrie, all of whom have offered her food. When she is first encountered in Radiant Dawn, Ilyana is observed to express her anger over being served inferior-quality food in meagre quantities while in prison, as can be seen in the following comment: "The food here... It was terrible, and...they hardly gave us any... I...will have vengeance." Furthermore, during her support conversations with Mia in Path of Radiance, Ilyana is presented as being so hungry to the point that that she collapses onto the floor, whereupon she begins to nibble Mia's boots.
A particularly hilarious quote that pertains to Ilyana's quirky appetite may be observed in the Info Conversation she shares with Heather, where she comments: "Heather. I'll need to remember her name...Heather. She likes to feed me.", as Heather happily saunters off in search of food sources for her.
Ilyana is once asked by Lucia if she happens to be of the Laguz race. This fact is never explicitly accounted for, as Ilyana herself appears to be genuinely unaware of her own background.
Ilyana shares a unique relationship with Zihark. This may be observed when she meets him in Chapter 1-5 of Radiant Dawn, where she comments that it has been "too long" since she last met him, and remarks that she often thinks of him. This relationship may also be observed in Chapter 3-7 when she speaks to Zihark, where he refuses to attack her, claiming that he has known her for a longer time than the other members of their armies. If the pair share a transferred A support from Path of Radiance, Ilyana will be able to recruit him, making him defect from the Daein Army.
Ilyana also appears to share an interesting relationship with Micaiah. This may be observed in Rivals Collide, where Ilyana strikes up a conversation with Micaiah when she is in close proximity with her. In this conversation, Ilyana expresses regret at being on the laguz side, as she harbors no ill will towards Micaiah. Ilyana then comments that both Micaiah's and her magic will be unable to severely injure the other. As Micaiah asserts that their fighting each other is wrong, Ilyana heatedly replies: "Of course it's wrong! The fact that we're fighting is all wrong! We don't even dislike each other!". When Micaiah is left speechless, Ilyana suggests that they forget the conversation ever happened. This relationship is left on a rather ambiguous note, as neither Ilyana nor Micaiah makes any mention of it after Ashera's wrath is wrought upon Tellius.
Ilyana's has a high Strength growth, meaning that she is less likely to lose AS from wielding tomes, a trait that may be able to compensate for her relatively low Speed. Despite her higher Strength growth, giving Ilyana staves instead of knives upon promotion is helpful, as knives require high Strength to be powerful in this game. Pairing her up with someone will fully utilize her useful Shade skill. The lower magic rating is compensated with her excelling in thunder magic, the strongest tome in the game; though thunder is less accurate, she has a decent skill growth rate to balance it out.
In Radiant Dawn, Ilyana returns as the only playable Thunder Mage. With her improved growths in Magic and Skill, the offensive problems associated with Thunder magic in Radiant Dawn may be considered to be compensated for. Ilyana may be considered to be a useful backline unit, with her class providing her with certain niche roles for players to pursue. Pairing her up with a front-line unit is recommended to allow her to fully utilize her Shade skill.
Ilyana is recruited in Part I, but then leaves the Daein Liberation Army to join the Greil Mercenaries for the most part of Part III. As this gives her arguably the best availability of any unit in the game, over-using her in Part I is not a good idea, as the Daein Liberation Army needs all the experience it can get to tone down the difficulty levels of Chapters 3-6, 3-12, and 3-13. If Ilyana is trained to a reasonable level and is chosen to be an Endgame character, she will potentially be able to reduce the difficulty level of Chapter 4-E, as she is capable of exploiting the blessed Rexbolt tome's ability to rend through the scales of the Dragon Laguz. This will essentially allow her to assist in the fight against Dheginsea himself, assuming her speed does not fall behind.
If given the proper training in Path of Radiance, data transfer will essentially result in Ilyana being more versatile in Radiant Dawn.
Ilyana: Thank you... And yes, Sothe... I don't want to fight...but I'm glad I'll get to fight alongside you again... Micaiah: Ilyana? If you're not up to it, don't feel pressured to fight. We can handle the soldiers. You look a little woozy. Are you sure you're going to be all right? Aimee: She's fine, Micaiah. She's always like that. Micaiah: But... Ilyana: I can fight... I'm...very angry... The food here... It was terrible, and...they gave us hardly any... I... will have vengeance. Micaiah: This girl takes her food pretty seriously. Interesting.
'Muston and the others are going to Daein, and I think I'm going to go with them. Thank you for everything, General Ike. Hmm... I hope they packed enough food... I'm pretty hungry...'
Ilyana is a corruption of Iliyana, a name that has been changed and altered throughout cultures in this order: Iliana (Spanish), Ileana (Spanish and Romanian), and finally Ileana-. In Roman folklore, she was kidnapped by monsters and rescued by a heroic knight, which is very similar to her situation in Path of Radiance.