"You mischaracterize us grievously," said the tick. "A truly successful parasite is subtle and harmless, taking so minimally of Nature's bounty that not a one could begrudge us our modest sup. Symbiosis is messy; predation is downright barbaric. Parasitism, proper parasitism, is as clean and easy as tossing a quarter to a homeless man on the street corner. Mercy blesses both the giver and the receiver, after all.
"What use to kill or main one's host? One who is gracious enough to give once may well give again and again. Rising up through violence to take the whole wallet, while potentially more immediately rewarding, is ultimately self-defeating. No, I think everyone would be a parasite, if they only knew how."
"My human is going to burn you with a match if I ever get home," the dog informed him.
"As is certainly his prerogative," the tick sighed. "Your blindness and gross insensitivity is, I have found, typical of canines. You lack understanding."
The dog paused to scratch vigorously, but to no avail. "I hate it when they get on your ear," the dog announced to no one in particular.
"Quite mutual. Dreadfully waxy. Still, needs must," said the tick.