Original setting and interesting opening. Just a few small grammar and spelling mistakes, nothing a bit of thorough proofreading won't fix. But this looks really good.

Wow, really gripping and tense story telling. Very skillful.

Well thought out and expertly written, with strong vivid and immersive narrative style. The world is unique and has a gritty yet vibrant feel to it. I like the amount of complexity, fantastical nature, yet believability and sense of dark realism the setting has to it. The dialogue richly portrayed the individual characters and was well written.
There was a paragraph or two towards the end that could have used a few spaces in between to break it up from being a large chunk, but that might just be my own personal preference; anyway, there were no errors overall and it felt well polished.
Anyone looking for a good story should set their eyes here. I look forward to reading chapters to come, and more of your work.

In a word: brilliant. The pacing is equatable to slow sting of peeling a band-aid off rather than performing one quick rip. The juxtaposition between the world of children and adults is more than adequately presented, along with the desperation of circumstances which bind them. The setting of the slums is nicely conveyed, both through descriptions, events, and of course by the contrasting specs of light we get from Lydia, or even the clothing prized by the gang members. Their grasping for what brightness is available in their sunless home is appropriate, simple human nature, but wrenching for the meagerness of such offerings. I think I'd have enjoyed some manner of personification of it all in Fen's mind: as though the slum itself were a person or thing, an entity attempting to eat him alive while at the same time capriciously helping him with the passages and walkways by which he moves freely and alludes the constables. But it's merely an aesthetic choice, and as for that, perhaps an ill-fitting one for Fen. You have the Joker in his pocket after all, which was an inspired touch.

Besides which, in Mr. Time we're given a fitting amalgamation of the dark characteristics of Junction's seedy bowels.

Fen's slowly dawning recognition of the Syn-dee-cat and Mr. Time's true nature is especially well done, the way he catches glimpses of the truth without grasping it's full meaning until it's too late; the essence of a coming of age tale. I feel a scrap of what Fen must have experienced at the end; a plunging from the story into the abyss of unanswered questions left over. Damn you. Heh. There are a handful of grammatical glitches to fuss over, but on the whole, a most enjoyable glimpse into the character. Well done.