Sprite Darter Hatchling: how to get the pet in WoW Forever
Sprite Darter Hatchling is a companion pet from Classic that returns in World of Warcraft: Forever. 
Sprite Darter Egg still summons it the way it did in Classic, according to the tooltip on the beta.
In short
| Item | Sprite Darter Egg |
| Source | Quest: Becoming a Parent |
| New in Forever | no, from Classic |
| Account-wide | yes, according to Wowhead |
How to get it
It is the reward of the quest Becoming a Parent, from level 37, for the Alliance.
The Sprite Darter Egg is also sold at the Black Market Auction House, by Madam Swyndle at Powderfuse Port in The Riverglades. More in the BMAH guide.
What changed since Classic
Wowhead’s database marks the pet as account-wide: learned once, it would be there for every character. Blizzard has not confirmed that itself.
More pets from the same source
Every pet of WoW Forever, with where it comes from, is in the pet guide.
Frequently asked questions
How do you get Sprite Darter Hatchling in WoW Forever?
It is the reward of the quest Becoming a Parent, from level 37, for the Alliance.
Is Sprite Darter Hatchling new in WoW Forever?
No. Sprite Darter Hatchling was already in Classic and returns in WoW Forever.
Sources: Wowhead