The orphans from Orgrimmar and Shatrath (blood elf) directly allow you to take all and any of the quests from the event questline - if they were completed last year. The orc orphan lets you take the finishing quest as soon as you call him for the first time - didn't complete the finishing quest for the blood elf last year, but the second tier ones are avaiable on first summon this year - similarly to the orcish orphan. Haven't completed the Dalaran ones last year to give info on those.