In "Thunderbolts" #21, Charles Soule and Carlo Barberi focus on intra-team conflicts. While Red Hulk, Venom, Red Leader and Deadpool are trying to get home from hell, Elektra and Punisher leave the base out of boredom. Everyone finds trouble, of course.
While Soule has dipped successfully into suspense and supernatural or psychological horror at times over his run on "Thunderbolts," his dominant or default tone is jokey and light, guided primarily by character interaction-based humor. The setting change and introduction of Ghost Rider last issue generates a lot of action and conversations in "Thunderbolts" #21, and as usual, Soule's dialogue feels fresh and easy.
Soule divides the story between the two settings. Ironically, the scenes in hell are much funnier, and Soule even makes a brief detour in the plot for a joke about a personal hell in which someone's greatest fear is being hairy. It's not a necessary move, but it shows the reader what Ghost Rider means by a "personal hell," and the ridiculousness of the scene adds to the comedy of the situation.
Although Ghost Rider was introduced to the team last issue, he didn't have significant interaction with them before the last scene, and "Thunderbolts" #21 gives him a chance to make the rounds, with the most significant conversations between Red Hulk, who Blaze sasses like a teenager talking to his dad, and Venom, the most approachable team member. However, Blaze mostly lies low, deferring decisions to Red Hulk and Red Leader, who broker a deal with Mephisto. Red Leader is hilariously keen on his self-delegated job as a contract attorney between the interested parties, and it's a good use of the character's personality and abilities.
Soule's narrative tone is darker for Elektra and Punisher, who are bored back at Thunderbolts HQ. Elektra restlessly pursues a new mission for money, and Soule picks up plot threads from almost a year ago as he explores the moral differences between the codes of the two killers. They pick at each other during the mission, moving towards the tension of a lover's squabble, before Soule leaves them caught off-guard by a surprise attack.
"Thunderbolts" #21 ends on a reveal of the identity of the usurper of Mephisto's throne, which will be catnip for readers who remember recent events in "X-Factor." Barberi sets up this scene nicely, and his transitions are likewise very smooth. However, his panels still lack depth, with the characters feeling like cut-outs. His faces aren't the most expressive and don't max out the potential in Soule's script, but they match the script without being jarring.
The coloring in "Thunderbolts" remains the weakest part of the creative team. Granted, "Thunderbolts" presents a challenge in how the characters are so dominated by the colors of blood and death, but all three colorists make boring or poor choices against these constraints, resulting in ugly background colors. Back at the base, Punisher and Elektra are colored as unimaginatively as the rest of the team in bland neutrals and cool tones.
"Thunderbolts" #21 is a transition issue with all the characters in play, and thus it doesn't feel as tightly plotted as some of Soule's more powerful issues, but it's not filler. Soule uses the space to link up hanging plot threads and to make room for Ghost Rider. The art is weaker than the writing, but due to Soule's dialogue and humor, "Thunderbolts" #21 is a solid read.