Cirno (InvaderJib)

Cirno is a semi-unitellgient ice fairy who naturally resides somewhere in Gensokyo. She is most well known for being incredibly egotistical, despite being considerbly weaker than a majority of Gensokyo residents. This often causes her to get into trouble with said other residents and end up in rather humilating situations. While she is more powerful than majority of the other fairies, her often irrational behavior prevents her from putting this to good use.

Personality
Cirno, as stated above, rarely thinks much about anything that isn't herself or how great she is, leading to her have difficulties getting along with others. Even though she seems to fancy herself a powerful geinus, her actual intelligence is fairly low, overlooking any kind of risk in her behavior and generally being ignorant to the world around her. However, it is apparently more than most of those on her level, since she is capable of reading.

Despite this she isn't incapable of caring for others, and seems to have a kind side through her self-admiration, though it doesn't show often. Her rather negative reputation does seem to get to her sometimes, though she mostly surpresses it.

Reimu Hakurei
Ever since she heard Reimu was "the real strongest person" (nobody knows her source on this) she decided to make it her mission to defeat her, in order to prove her place. Unforutantely, Cirno has about as much luck with this as you'd expect, and she seems to resent her for it, accusing her of 'constantly cheating.'

Other times their relationship can be somewhat friendly, at least from her side, as Cirno seems to begrudginly look up to her like a child would.

Daiyousei
Daiyousei seems to be one of the few Cirno cares for and is consistently friendly towards, albeit being no more humble towards her. Daiyousei herself is one of the few to actually respect Cirno.

Suwako
Cirno hates her for constantly ruining her hobby of freezing frogs, calling her a "heartless bully." Suwako herself doesn't seem to care much about this.

Clownpiece
Cirno was immediatly intimidated by her after hearing a fairy "way stronger than her" had entered Gensokyo, and like Reimu, she immediatly declared her a rival. Clownpiece doesn't even care at all and seems to jokingly treat her like a friend.

The Three Faeries
She tends to shift between rivals and friends with them, depending on the situation.