Rappel, and fellow prison inmates Daniel Grech, Alex Bourne, and Jeremy Reid filed in from the cells one by one.

They were each charged with recklessly inflict grievous bodily harm against one brother, and assault actual bodily harm against the other.

They were all remanded in custody.

They did not enter pleas.

With a grin or a nod each inmate acknowledged the fifth man accused of the assaults, who sat in the ACT Magistrates Court public gallery waiting to be charged.

When called, Isileli Paea Taholo, 31, was charged with aiding and abetting the four to assault one brother, and assaulting the other.

He is currently in immigration detention.

Prosecutors said they may apply for the man to be taken into the custody of the territory at a later date.

He was led from court in custody and flanked by several Serco guards from immigration detention.

He did not enter pleas.

The five men are accused of bashing the two Indigenous men in their cells in the Alexander Maconochie Centre on August 7.

Both men were taken to hospital.

One was returned to jail the same day, while the other was admitted to hospital and returned the next evening.

Corrections Minister Shane Rattenbury said at the time there was "extensive CCTV footage of this incident".

Rappel, 43, is serving 32 years in prison for killing his partner Tara Costigan with an axe as she held their newborn.

Bourne, 30, who has links with the Comanchero, is waiting to be sentenced for blackmail and assault offences.

Grech, 28, also linked to the Comanchero, is serving time for shooting a rival bikie as he smoked on his porch.

Reid is 26 years old.

All five will return to court on January 18.