Which man in the picture above are you drawn to most? Remember, this is an exercise on flashback, so your point of view character is remembering or flashing back to the scene above. What's going on in his present-day life that causes him to remember this moment?
Is the present day moment filled with expectation? Regret? Is this an exciting moment that now offers hope in the present-day situation? What was the relationship between the two men? Has one of them died in the present day? Have they made contact after many years? Does one have damaging information from the past that affects the other's life?
The What If's are limited only by your imagination. Anything is possible, and that's the fun of writing fiction.
Always ask yourself why your character is having the flashback. Will his memory affect the present day plot? It should be. A flashback that is there only for the sake of giving information to the reader is lazy writing.
Another point to remember: In terms of technique, once you're in a flashback, the other four ingredients of the scene all come into play. You don't want to tell what's happening in the flashback. You want to show the flashback as a complete scene!