The passages in bold type in your examples are not complete clauses.
There is nothing grammatically wrong with either sentence; native speakers say things like that all the time. Good writers, however, do not write like that because the sentences are unclear.
In your first example, what does being charismatic and articulate have to do with being fearful or having warped logic? Something is missing. Perhaps something like: "Nevertheless, his warped perception made him fearful." Now that suggestion may not reflect what you wanted to say at all, but just tacking on "his main source of fear being derived" does not relate to the first part of the sentence. You may know how the two parts relate, but your reader will not.
The second sentence is considerably clearer, but can be made to express exactly what I am reasonably sure you want to convey. There is a causal relationship that is not made explicit.
"His memories of Caroline are clearly something he holds precious because his features contort with pain as he tells his story."