Three types of the rare fey will be discussed here: Springlings, Pixies, and Satyrs.
Springlings are a collection of plant-like creatures that each have developed a way to survive in the world. Some are called "Hamadryads" by other races because of their resemblance to the beautiful dryads of legend, while the more fungi-like are often called "Myconids". Others even call themselves Wilden because of their pride in being creatures of the wild, but regardless they are all plant-like humanoids each with his or her own way of doing things.
Pixies are a curious lot: they're extremely tiny creatures, smaller than even the gnomes and halflings, and are often helpless when tackling things individually. However, once in awhile -- and for some odd reason it tends to be the pixie with the worst case of dandruff (you really wouldn't want to imagine the alternatives to explaining how "pixie dust" is made and extracted) -- exceptionally adventurous and capable pixies separate from the swarm and wander off into the world.
Satyrs are a fun-loving group of goat people, who are often seen with an unusual set of windpipes as a musical instrument. If any satyr comes out of the forest and into the city, luck is sure to follow.
... just don't expect that luck to be the good sort.
Simple ReflavoringFor GMs who want a quick and dirty conversion that doesn't require the features below, feel free to reflavor Dwarves as Springlings, Gnomes as Pixies, and Demonspawns/Tieflings as Satyrs. For those who want more distinct mechanical differences, see below.
Springling+2 CON or CHA
Biotal Defense: Once per battle as a reaction to a missed melee attack, make a check with your highest attribute against the nearby opponent that has the highest PD. On a success, you can cause one engaged opponent to be dazed until the end of their next turn.
Author's Note: Please replace the word "biotal" with the type of defense your springling character uses. For instance, Pheromone defense would likely involve charming enemies with enticing scents, while Thorn defense would likely involve either discouraging or hindering the enemy's attacks with the sudden appearance of thorns.
(Adventurer Feat): You can expend the use of your Biotal Defense to gain a +2 to any Charisma-based check, as long as it is appropriate to the method you normally use as defense.
(Champion Feat): Once per day you can affect each nearby enemy, instead of one engaged opponent. At the end of a fight, you can either roll a 16+ or spend a recovery to regain the use of this feat.
Pixies+2 DEX or CHA
Pixie Dust: Once per battle you can cause yourself or a nearby ally to fly to a nearby location as a move action.
(Champion Feat): You can instead expend the use of your Pixie Dust as a standard action to manipulate light immediately around you for a round. Normally this could either render you completely invisible for a round, or amplify the glitter of your pixie dust to create an astounding burst of light that would have you make a Charisma-based attack versus each engaged enemy and cause them to become dazed, but you'd probably want to discuss the effects and implications with the GM ahead of time as well.
Author's Note: If the GM is cool with it, this feat will allow you to treat Pixie Dust as a spell, allowing you to use this as part of a ritual if you are able to cast rituals (either by taking the wizard or cleric class, or taking the ritual caster feat).Small: Pixies have a +2 AC bonus against opportunity attacks.
Author's Note: Even though they may appear to be smaller than gnomes or halflings, I personally see no reason why their basic mechanical benefits involving size should go beyond that of other small folk. In fact, the mechanics that 4E introduce basically make them mechanically small (more or less), even though they were written as Size: Tiny. I also didn't bother writing down the technicalities involving pixie flight and what not, under the assumption that it's the logical explanation for pixies being able to keep up with the rest of the group in terms of movement (much like how gnomes and halflings in 13th Age aren't actually penalized movement-wise for being small).
Satyr+2 CON or DEX
Satyr's Charm: Whenever you make a Charisma check involving charming, deceiving or scaring an opponent, roll a die to determine if you can re-roll the result. If your roll is equal to or lower than the escalation die, you can roll that Charisma check a second time and choose whichever result you want.
After making the Charisma check, roll a d6. Each time you get to re-roll your Charisma check, the die you roll increases by one step in the following progression: d6, d8, d10, d12, d20. If you get to re-roll your Charisma check after the d20, you can no longer re-roll your Charisma check for the remainder of that battle.
(Champion Feat): You can roll two of the dice used for Satyr's Charm (e.g. 2d6 instead of 1d6) and pick either result.Author's Note: Rather than explicitly give the Satyr a 1/battle dazing ability, I decided that everyone who wanted to bluff or intimidate an enemy into a compromising position should be able to do so, it's just that Satyrs simply do it better using their music and their natural charm.