He goes to Ariadne, because who else was he going to go to? Cobb was the closest thing Arthur had to a friend, but he is at home with his kids, and Eames isn't about to barge in there, bleeding and swearing, to make Cobb help. Yusuf is back home in Mombassa, Saito is busy as usual, all he has is the hope that Ariadne's free and willing to put his shoulder back where it belongs.
Driving a stick shift is more difficult than he remembers, but then he hasn't had to drive it one-handed in a long time. Ariadne, luckily, is renting a shitty walkup not too far from the warehouse, and he somehow, miraculously, manages to make it all the way up her ten flights of stairs before collapsing, banging his head into the door on his way down.
When he opens his eyes, she's looking at him with the strangest expression. Her face is always pale, so she hasn't gone white, exactly, but there is a definite sense of terror there, barely restrained. "Whu…" he clears his throat. "What's wrong?"
She just stares at him, and suddenly he remembers. "Oh, god, Ari, it's nothing, trust me, it's not as bad as it looks. I just, my shoulder. I need my shoulder and then I'll be out of your way."
"I can't set your shoulder, Eames, I don't know how." Her face still has that strange look. "And it's hardly nothing, you look like a train hit you. What the fuck happened?" Ariadne's voice is always strangely even, regardless of how panicked or freaked out she is. The only clue to her distress is her language, and Eames flinches at the curse. It means she's scared, and upset, and scared some more, and it's his fault she feels that way.
"Love, I'm sorry, I really am, but I assure you, it's nothing. Just some bumps and bruises and this shoulder. I need you, Ari, I can talk you through it. I've popped enough shoulders back in to know how, it's just a touch tricky to do it myself."
Ari's hitching breath, holding back her sobs, does nothing to muffle the horrifying sound of Eames's shoulder going back to where it belongs. She doesn't take her hands away for a moment, just leaves them there, and Eames reaches his good arm up to stroke her hair. "You did a marvelous job, love, and I'm sorry again."
She shakes his hand off, leaves the room, slams and locks the door down the hall. Eames feels sharp stabs and dull aches from every inch of his battered body, but he doesn't have time for this shit. Arthur is somewhere doing god knows what, and everything depends on Eames finding him in time.
He can't think here, with Ari's cluttered living room full of architecture and photography shit, with her pictures of marks looking at him. He leaves, feeling like traitor, hoping against hope that Ariadne will forgive him someday for this.
"If I was Arthur," he says to himself shakily as he inches down the stairs, "where would I go?" If it was Eames, he'd go to a pub, but Arthur's never been that way. Arthur would go home, or would drive into a tree and kill himself because Arthur can't deal with pain, emotional pain, at all, and if Arthur's face when he left is anything to judge by, Eames wouldn't be surprised if Arthur is flashing back and forth between the dream and reality, and swiftly losing track of everything. Eames has done that enough times to recognize it. He isn't Catholic anymore, but as he gingerly pulls out of Ari's parking lot, he finds himself whispering prayers to saints and angels that Arthur isn't dead, that Arthur isn't dead, that Arthur isn't dead.