B777 Captain reported engine failure on auto throttle spool up required a rejected take-off and a return to the gate for maintenance action.

Narrative

Engine failure occurred during auto throttle spool up for take-off due to aircraft malfunction. On take-off roll; aircraft experienced engine failure on the right engine first identified departure from center line from asymmetric thrust; followed immediately by EICAS warnings; take-off was aborted. Directional control regained. ENG Fail R EICAS observed. CONFIG EICAS observed. After First Officer made initial call to cabin to remain seated; I took over cabin communication while he worked checklists and attempted to communicate with ARFF (Airport Rescue and Firefighting). Rejected Take-off Checklist initiated and completed for ENG FAIL R. During event; Flight Attendants reported observing smoke on right engine via Purser and made second call from 3R detailing color change from white smoke to black smoke. I directed F/O (First Officer) to secure engine immediately. Three steps out of checklist sequence. ARFF on scene; but did not initially reply for status request on discreet frequency. I attempted to get status check relay from ARFF via Tower. I communicated with Purser on status. I went through briefing with Purser and advised I am trying NOT to evacuate. Once contacted and ARFF did not observe fire; I directed F/O to request ARFF escort to Gate XX. After gathering ourselves and advising Purser of intentions after landing flows and APU started for gate return; cabin was advised to remain seated until seat belt sign was off for gate return. Aircraft taxied to Gate XX with ARFF in tow. Flight deplaned normally. Purser called crew to first class for debrief. As we debriefed; discovered one Flight Attendant noticed flames in engine; but could not get the word to flight deck due to busy PA/Intercom. Upon inspection; both pilots observed burn marks and scarring on pylon indicating that a fire likely occurred.