At 26, Marshall compiled a 3.86 ERA with 58 strikeouts in 65 1/3 innings in 2008, splitting time as a starter and a reliever.
The left-handed Fontenot hit .306 last season as a reserve, including .360 after the All-Star break.
By re-signing Ryan Dempster, the club is set with four-fifths of its rotation, leaving Jason Marquis and Marshall to battle it out for the fifth spot.
Late last week, MLB.com learned from a source that no deal involving Teahen had been discussed by Kansas City general manager Dayton Moore and his Cubs counterpart, Jim Hendry.
Teahen, eligible for salary arbitration, is expected to earn $3.1 million to $3.25 million this year.
Teahen's average slipped 30 points from its 2007 level -- to .255 -- but he still banged 15 homers and had 59 RBIs this past season. He has played left field, right field, third base and first base, so his versatility is valued.
Nick Zaccardi is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.