Spike

Spike is a purple and green young male dragon. He is Twilight Sparkle's friend and assistant, and one of the main characters of My Little Pony Friendship is Magic. His ability to magically deliver scrolls to and from Princess Celestia with his fire-breath is featured in most episodes. Spike has a deep crush on Rarity.

Personality
Spike is occasionally sarcastic and sometimes laughs at others' misfortunes; in Bridle Gossip, he comes up with parodies of the ponies' names after their exposure to poison joke; Hairity, Rainbow Crash, Spittie Pie, Appletini and Flutterguy, however he can't think of a nickname for Twilight Sparkle and says "I can't even work with that." When the ponies leave, he comes up with the nickname Twilight Flopple. In Winter Wrap Up, he makes fun of Twilight's terrible nest-making and skating skills. However, he is very helpful and supportive towards Twilight in Lesson Zero. For instance, Spike was the only member of the main cast to take Twilight's concerns about missing a report to Princess Celestia seriously, unlike the other ponies. He is often defensive about his masculinity and dismissive of things he considers "girly", although his outward disdain is often a front. In The Ticket Master, for instance, Spike scoffs at the idea of attending the "girly Gala gunk" throughout the episode, but is overjoyed when Princess Celestia sends him a ticket at the end.

He's a fun-loving dragon: he enjoys the welcome party that Pinkie Pie throws for Twilight in Friendship is Magic, part 1, and scarfs down candy in Nightmare Night.

Spike sees himself as athletic and smart; in Read It and Weep, when Twilight says to Rainbow Dash "just because you're athletic doesn't mean you aren't smart", he replies "yeah, just look at me", curls his arm and kisses his bicep. Twilight and Dash were not impressed by this display, and he irritatedly walks off. He imagines himself to be a debonair knight in a fantasy sequence in A Dog and Pony Show, suavely and easily defeating the Diamond Dogs to save his "Lady Rarity." He admits to Pinkie Pie in Party of One, somewhat embarrassed, that "sometimes, when no one's around, I do this," then pulls up a mirror, flexes his arms, sticks out his chest, and says, "Lookin' good, Spike, lookin' real good", though he covers his face in bashfulness afterwards.

Rarity
Spike develops a crush on Rarity the moment he sees her in Friendship is Magic, part 1. He goes to great lengths for her affection. In Green Isn't Your Color, he gladly offers his body as a pincushion for Rarity to use, while she designs a dress. In Boast Busters, he tries to impress her with a mustache conjured through Twilight's magic, however this attempt was met with little success. Spike postures that maybe the mustache was not enough, and he considers adding a beard, too.

Spike is protective about Rarity in A Dog and Pony Show. Even though he is all but defeated by the Diamond Dogs, he still tries to find ways to rescue Rarity, like using the gem she gave him earlier, which he holds very dear, as bait for the Diamond Dogs. There is a fantasy sequence of him rescuing Rarity from the dungeon as a debonair and masculine knight, which ends when his fantasy clashes with reality and he nearly kisses Applejack, who was standing next to him.

Despite all of this, Rarity does not really acknowledge his feelings to her. He even treats it as a secret in Green Isn't Your Color, though his feelings are so obvious to other ponies that he is shown wearing a shirt with Rarity surrounded by a heart as a visual gag. Pinkie Pie, who is privy to the "secret" as much as the other ponies, still acts very surprised when Spike reveals his secret to her. When he and Rarity plummet from a mountainside to a likely demise in Secret of My Excess, he tries to confess his feelings to her, but she shushes him before he finishes his sentence, implying she already knows. In Dragon Quest, Rarity shows a more caring and more sensitive feeling for Spike, and like in Secret of My Excess, calls him Spikey-Wikey.

Appearance
Spike's appearance is based on his Generation 1 incarnation rather than his Generation 3 version, with a few modifications done by Lauren Faust. He is also the second member of the main cast who was part of the original My Little Pony series, next to Applejack. Throughout all of his incarnations, in Generation 1, he's consistently been a baby dragon with green spikes, and occasionally his body is pink. In his G3 incarnation, he's a thousand-year old dragon with orange spikes, purple hair, and occasionally a blue body.

Skills
Spike has the ability to transport scrolls back and forth between Twilight Sparkle and Princess Celestia. He sends notes by breathing magic fire onto them and blowing them into the air. He sends multiple notes all at once in Griffon the Brush Off, and transports tickets to the Gala in The Ticket Master. He does have his limits, though: Twilight finds him curled up on the floor, groaning and clutching his stomach, after Princess Celestia sends him too many scrolls in The Return of Harmony Part 2. In Feeling Pinkie Keen, Celestia comes to collect one of the scrolls herself, right as Spike is about to send it from the library's terrace.

Spike's fire has different effects on objects in different situations. In Griffon the Brush Off, his fiery hiccups cause Princess Celestia to be showered with a large number of scrolls, which he can also do voluntarily. In Owl's Well That Ends Well, he accidentally incinerates a book with a sneeze. He has also used his fire to cook food in Over a Barrel and A Bird in the Hoof.

In the episode Griffon the Brush-Off, Spike mentioned he was fireproof, but in Owl's Well That Ends Well, his spines were slightly burned by the wild dragon.

Lauren Faust elaborated on her take of Spike's magic fire breath, which is covered in a section below.