Who is Dyne?
During a business trip, about 4 years before the present time of the game, Barret and Dyne were away from Corel and when they came back, the town was on fire. When they reached the bridge to Corel, they met the people who caused the fire, Shinra. Scarlet was in charge and ordered the troops to shoot at them. Dyne slipped and nearly fell off a cliff, but Barret was able to grab his left hand. The Shinra troops and in particular, "kyahahaha" Scarlet, kept shooting and shot off Barret's right hand and Dyne's left hand. Dyne fell supposedly to his death. Barret got a machine gun grafted into his hand to get revenge on the Shinra.
Barret went in the burning town and found Dyne's daughter, Marlene, and adopted her. Barret left the town and became leader of Avalanche. He led Biggs, Wedge, and Jessie. Later on, Shinra decided to get rid of Avalanche by just destroying their headquarters, Sector 7. Biggs, Wedge, and Jessie were killed along with all the other inhabitants of the Sector 7 slums.
Cloud was handed leadership of Avalanche. On their way of chasing Sephiroth, they happen to come by North Corel and rested at Gold Saucer. The entire team however was captured for a crime they didn't commit and were thrown into Corel Prison. There, the entire team finds out about Barret's past. Barret also discovers Dyne is still alive and in fact the head of Corel Prison. Dyne has totally lost it and the two men fight after a pretty intense conversation.
Dyne: I hear her voice, Eleanor's voice. Begging me... not to hate you
rotten guts. That's why I didn't hunt you down...
Barret: ...I know I was stupid. I'm not asking you to forgive me.
But... What're you doin' in a place like this? Why ya wanna kill those
that ain't even involved? Why?
Dyne: ...Why!? The hell do you care for!? Are the people killed going
to understand 'why'? Are the people of Corel going to understand just
hearing Shinra's excuses? I don't CARE what the reason is! All they
give us are artillery and stupid excuses... What's left is a world of
despair and emptiness...
Barret wounds Dyne only to realize that Dyne's death was inevitable.
Dyne: Back!! ...it wasn't just my arm...... back then...... I lost
something irreplaceable. I don't know where I went wrong...
Barret: Dyne... I don't know either, man. Is this the only way... we
can resolve this?
Dyne: I told you... I ... I want to destroy everything... Everything...
This crazy world... Even me...
Barret: An' what 'bout Marlene? What's gonna happen to her!?
Dyne: ...Think about it... Barret... How old was Marlene back then...?
Even if I did go to her now... she wouldn't even know me... And what's
more... Barret... These hands are a little too stained to carry Marlene
anymore...
Barret: ......
Dyne: Barret... Give that pendant to Marlene... It was... Eleanor's...
my wife's memento... (gave the pendant to Barret)
Barret: all right...
Dyne: ...wow... Marlene's... already...... 4...... Barret...
Don't...... make...... Don't ever make Marlene...... cry...
Dyne then commits suicide by jumping off the cliff. The corruption of their world changed Dyne into a helpless creature of despair. Although he ended his life, he ended it with the happieness
in his memories of his precious daughter, Marlene.