Looking for the right word to express my "skin in game" when talking about someone else

For everyone who has a loved one in the fight, prayers are going out for each and everyone! Lord, keep them ALL safe and bring them home! This man is my __________ in the fight.

There are two closely related idioms, variations of each which can be referenced in the question.

The first is skin in the game:

[Definitions]
A stake; something at risk, especially with regard to money and investments.

The second, which has the same meaning but which a variation of can be used as a drop-in to the example sentence, is have a dog in this fight:

[Definitions]
To have a personal stake in an issue.

Perhaps used both metaphorically (because it's an idiom) and literally in an analogical sense (because it's also talking about an actual person) the example sentence could include the following variation:

For everyone who has a loved one in the fight, prayers are going out for each and everyone! Lord, keep them ALL safe and bring them home! This man is my dog in the fight.