The judge was similarly cautious about their approach to Wallace-Loretz and Gillman-Harris.
"You might be critical of them and those responsible for their care, but you'll also feel inevitable sympathy for the defendants and their families. These young men are facing the most serious of charges," Justice Toogood said.
"You will have had your emotions stirred. There's nothing wrong with that. It's what makes us human."
The Crown case is that the teenagers smuggled a bat into the motel room and beat the man to facilitate the theft of cash, a credit card, a phone and a Range Rover.
Prosecutor David Johnstone said the text messages exchanged between the defendants showed the plan to "roll" Mr Gillman-Harris was a "joint enterprise".
As well as the murder charge, the teens are jointly facing counts of theft and dishonestly taking a motor vehicle.
Justice Toogood told the jury it must come to independent verdicts on all six charges and just because one defendant was guilty or not guilty of an individual charge, it did not automatically mean the other was too.
The defence case is that Mr Gillman-Harris made a violent sexual advance towards Nattrass-Berquist.
Wallace-Loretz intervened, striking the victim over the head with a bottle - self defence, according to their lawyers.
Justice Toogood said anyone was justified in using force against someone in defence of themselves or another person if the force was reasonable in the circumstances as they believed them to be.
The burden was on the Crown to disprove that, the judge said.
"This is a tragic case in many respects. What happened in hotel room . . . will already have had a profound and everlasting effect on three families," he said.
"For them, whatever verdicts you reach, life will never be the same as it was on Christmas Day that year 2014."
Justice Toogood will finish his summing up tomorrow morning before the jury begins deliberation.
WHAT THE CROWN HAS TO PROVE BEYOND REASONABLE DOUBT FOR A MURDER CONVICTION:
1. There was an unlawful act causing death
2. That act led to an operating and substantial part of the cause of death
3. The defendant had murderous intent (any of the three types)
(*If only the first two steps are proven it is manslaughter)
TYPES OF MURDEROUS INTENT:
1. Where someone intends to kill the victim
2. a) The defendant meant to cause bodily injury
b) The defendant knew the injury they intended carried a real risk of death
c) The defendant was reckless as to whether the victim died or not
3. a) The defendant meant to cause grievous bodily injury
b) The violence was used to facilitate the commission of a robbery or avoid detection in the commission of the robbery