As usual, Favre saga full of intrigue

Brett Favre plans to meet with Vikings coach Brad Childress later this week and discuss the possibility of coming out of retirement -- again.

He turns 40 in October. The biceps tendon in his throwing arm has a partial tear. The NFL's iron man is finally seeing that his body is starting to grow old, especially in the later parts of seasons.

Still, the thought of Favre returning to the NFL is -- once again -- the most compelling story in the NFL. Here are five things that make this possible deal with Minnesota intriguing.

1. The revenge factor: Packers general manager Ted Thompson is one of the nicest men in the NFL. He's quiet. He's unassuming. He works behind the scenes, displaying very little ego. Favre dislikes him enough that he would park the tractor at his farm and endure the pain of playing another season. Favre didn't like when Thompson refused to re-sign some of his favorite veteran offensive linemen. He couldn't believe Thompson wouldn't trade for Randy Moss.

Now, Favre is thinking about putting on the colors of one of the Packers' most bitter rivals. Favre's return to the NFL last year was on Thompson's terms. Favre had to play in the AFC for the Jets, not in the NFC. The Packers got a third-round pick, but Thompson, to protect the Packers, inserted a clause into the trade that would have made the Vikings give up three first-round picks if the Jets traded him to Minnesota. Following his official release from the Jets, Favre is free of any contractual obligation and can sign with the Vikings for no draft-choice compensation. It's ultimate revenge.

2. Salary questions: What would the Vikings pay Favre, who was scheduled to make $13 million had he played for the Jets? The Vikings have about $17 million of cap room, and the team's owners are huge fans of Favre. Still, the Vikings aren't negotiating against anyone. Do they offer him $13 million? Plus, if they offer him less, will Favre be insulted?

The other fascinating part of these talks is what is at stake in Green Bay. The Packers have offered him a post-playing contract that could be worth more than $20 million. That contract gives the Packers the ability to market Favre merchandise, which always will be popular in Green Bay. Signing with the Vikings could cancel that rich financial offer for Favre.

3. Offseason workouts: How lenient will Childress be in letting Favre stay away from offseason workouts? It was no accident that Favre called Packers coach Mike McCarthy the day after the final offseason practice last year. Favre doesn't like offseason workouts. He doesn't like minicamps. He'd like to find a way to avoid training camp, but that's not going to happen. Childress is going to want Favre to do as much as he can in Minnesota, particularly participating in the May 29 minicamp.

Favre hasn't been training this offseason, so he probably feels he won't be able to throw by May 29. He'd prefer to hire a trainer and a quarterback coach and work in Mississippi. If Childress mandates too much offseason participation, it could be a deal-breaker for Favre.

4. A dome as a home: Remember how Favre used to struggle in domed stadiums? He had some of his worst games in the Metrodome and Silverdome. Of late, though, the air-controlled climate seems to favor him. In many ways, the Metrodome may be better for him than playing those December or January games in Lambeau Field or the Meadowlands.

In 16 career games in the Metrodome, Favre has completed 63.8 percent of his passes and thrown 24 touchdown passes. In his last five games in the Metrodome, Favre completed 68 percent of his passes. He had 12 touchdown passes and only two interceptions in those five games. Playing in a controlled climate might be good for him.

5. Potential payoff: The end result is the most intriguing. If Favre can stay healthy, he might be able to make the Vikings two or three games better during the regular season because he can win the shootouts that current starter Tarvaris Jackson has been unable to win the past couple of years.

But Favre is almost 40, and 40-year-old quarterbacks have bodies that can fail late in the season. The biceps problems contributed to Favre and the Jets losing four of their last five games last season. The Vikings have to consider the possibility of another similar drop-off, but Childress can worry about that in December. His mission now is to see if he can get Favre in a Vikings uniform.

John Clayton, a recipient of the Pro Football Hall of Fame's McCann Award for distinguished reporting, is a senior writer for ESPN.com.