Thus, if I'm not mistaken, one can say "Вампир сосёт мою шею" ("The vampire is sucking my neck") BUT "Вампир высасывает мою кровь ("The vampire is sucking-out my blood").
If we talk about vampires we would hardly ever say "сосет шею" we would rather say "кусает шею" but we would use both "сосет кровь" and "высасывает кровь".
Though we can say "сосет палец" about a baby, "сосет лапу" about a bear, etc.