Jesus had prayed for Peter that his faith would
not fail. His prayer would make the difference.

When Peter repented and was fully converted,
would strengthen his brethren.

Later we see Peter in 1 Peter 5:10 doing that
very thing: "But the God of all grace, who hath
called us unto his eternal glory by Christ Jesus,
after that ye have suffered a while, make you
perfect, stablish, strengthen, settle you"