The Unexpected Trek (Hobbit/Star Trek Crossover)

Elves

Elves are born about one year from their conception. The day of their conception is celebrated, not the actual birthday itself. Their minds develop more quickly than their bodies; by their first year, they can speak, walk and even dance, and their quicker onset of mental maturity makes young Elves seem, to Men, older than they really are. Physical puberty comes in around their fiftieth to one hundredth year (by age fifty they reach their adult height), and by their first hundred years of life outside the womb all Elves are fully grown. Elven bodies eventually stop aging physically, while human bodies do not.

Elves marry freely and for love early in life. Monogamy is practiced and adultery is unthinkable; they marry only once (Finwë, first High King of the Noldor, was an exception, as he remarried after his first wife died).

Spouses can choose each other even long before they are married, thus becoming betrothed. The betrothal is subject to parental approval unless the parties are of age and intend to marry soon, at which point the betrothal is announced. They exchange rings and the betrothal lasts at least a year, and is revocable by the return of the rings; however, it is rarely broken. After their formal betrothal, the couple appoint a date, at least a year later, for the wedding.

Only the words exchanged by the bride and groom (including the speaking of the name of Eru Ilúvatar) and the consummation are required for marriage. More formally, the couple's families celebrate the marriage with a feast. The parties give back their betrothal rings and receive others worn on their index fingers. The bride’s mother gives the groom a jewel to wear (Galadriel's gift of the Elfstone to Aragorn reflects this tradition; she is grandmother to his betrothed, Arwen, Arwen's mother Celebrían having left Middle-earth for Valinor after grievous psychological injury after her capture by Orcs and liberation by her sons).

The Elves view the sexual act as extremely special and intimate, for it leads to the conception and birth of children. 
Extra-marital and premarital sex are unthinkable, adultery is also unheard of and fidelity between spouses is absolute. Yet separation during pregnancy or during the early years of parenthood (caused by war, for example) is so grievous to the couple that they prefer to have children in peaceful times. Living Elves cannot be raped or forced to have sex; before that they will lose the will to endure and go to Mandos.

Elves have few children, as a rule (Fëanor and Nerdanel were an exception, conceiving seven sons), and there are relatively sizeable intervals between each child. They are soon preoccupied with other pleasures; their libido wanes and they focus their interests elsewhere, like the arts. Nonetheless, they take great delight in the union of love, and they cherish the days of bearing and raising children as the happiest days of their lives.

The Elves, particularly the Noldor, preoccupy themselves with various things such as smithwork, sculpture, music and other arts, and of course, what to eat. Males and females can do almost everything equally; however, the females often specialize in the arts of healing while the males go to war. This is because they believe that taking life interferes with the ability to preserve life. However, Elves are not stuck in rigid roles; females can defend themselves at need as well as males, and many males are skilled healers as well, such as Elrond.

Eventually, if they do not die in battle or from some other cause, the Elves of Middle-earth grow weary of it and desire to go to Valinor, where the Valar originally sheltered their kind. Those who wish to leave for the Undying Lands often go by boats provided at the Grey Havens, where Círdan the Shipwright dwells with his folk. Elves are naturally immortal, and remain unwearied with age. In addition to their immortality, Elves can recover from wounds which would normally kill a mortal Man. However, Elves can be slain, or die of grief and weariness.

Elves sometimes appear to age under great stress. Círdan appeared to be aged himself, since he is described as looking old, save for the stars in his eyes; this may be due to all the sorrows he had seen and lived through since the First Age. Also, the people of Gwindor of Nargothrond had trouble recognizing him after his time as a prisoner of Morgoth.

Elves value children, beauty and simple arts.

(If I missed anything please let me know and I'll fix it!)