Treyvon Pritchard and his brother Kadin committed to Rugby Australia in July, despite interest from the incoming PNG Chiefs and, for Treyvon, the Sydney Roosters.
The younger Pritchard is contracted until 2029. He said rugby's international opportunities helped convince him to stay.
"Rugby union ... it can take you anywhere," he said.
"Boys from the Reds playing in Italy, some to France, England."
"That opportunity is so great, and such a big thing the game has to offer and something that persuaded me, kept me in the game."
The Reds left on Wednesday for a four-match pre-season tour of Japan and Italy, including two games against Saitama Panasonic Wild Knights, then matches against an Italy XV and Benetton in Treviso.
Pritchard hopes to return later this month after a serious foot and ankle injury at July's U20 world championship. The hip-drop tackle that caused it went unpunished but has since been specifically outlawed under revised World Rugby rules.
"I've been running the last two weeks, and hoping to progress a bit faster over the next two weeks and maybe catch a game towards the back end of it," he said before flying out.
"With them (the Reds' strength and conditioning team) coming along too it's only going to progress."
The 19-year-old earned Rugby Australia's rookie of the year award after 12 Super Rugby Pacific appearances. A Wallabies call-up had looked possible before his injury; his brother Kadin, a Brumbies centre, was called up when suspensions and injuries reduced the Test side's midfield options.
Strong tour performances could return Treyvon to Wallabies contention, with the team playing England, Scotland and Wales this month and next year's Rugby World Cup on home soil.
The touring Reds, now coached by former Blues title-winning mentor Vern Cotter, also include recruits Izaia Perese and Cadeyrn Neville, plus Wallabies contenders Matt Faessler, Aidan Ross, Zane Nonggorr and Tom Lynagh.