Vanilla Custard is actually rather scrummy. I've been working on a VC flavour for ages and I can't stop vaping the latest version, am not sure what to call it yet probably VVCC.
Absinthe isn't green, at least the flavouring isn't. the green colour in absinthe the liquor comes from chlorophyll that leaches out of the leaves of the herbs added to it after it's distilled (distillation removes colours)
It has in it:
anise, florence fennel and grande wormwood as well as sometimes herbs including angelica root, coriander, dittany leaves, hyssop, juniper, nutmeg, melissa, star anise, sweet flag, and veronica.
DV absinthe is green coloured, there are probably other green coloured flavourings too, but they use green colouring as far as I know.
Colouring is probably best avoided for vaping. It might be perfectly safe, it might cause problems and you don't need it to be in there so why take the risk?