Python 3, 2×497 + 619608 = 620602

import operator as o l='' w='' d={} p={} s=0 def z(x,y): return sorted([(k,v) for k,v in x.items() if k.startswith(y)],key=o.itemgetter(1)) def f(c): global l,w,d,p,s r=' ' if c in ' \n': s+=1 if w in d:d[w]+=1 else:d[w]=1 if w: if l: t=l+' '+w if t in p:p[t]+=1 else:p[t]=1 n=z(p,w+' ') if n:g=n[-1];l=w;w='';r=g[0][len(l)+1] else:l=w;w='';r='t' else: w=w+c;m=z(p,w) if m: g=m[-1] if g[0]==w: if s>12:s=0;r='\n' else:r=g[0][len(w)] return r 

Python 3, 2×497+619608=620602 2×496+619608=620600

import operator as o l='' w='' d={} p={} s=0 def z(x,y): return sorted([(k,v) for k,v in x.items() if k.startswith(y)],key=o.itemgetter(1)) def f(c): global l,w,d,p,s r=' ' if c in' \n': s+=1 if w in d:d[w]+=1 else:d[w]=1 if w: if l: t=l+' '+w if t in p:p[t]+=1 else:p[t]=1 n=z(p,w+' ') if n:g=n[-1];l=w;w='';r=g[0][len(l)+1] else:l=w;w='';r='t' else: w=w+c;m=z(p,w) if m: g=m[-1] if g[0]==w: if s>12:s=0;r='\n' else:r=g[0][len(w)] return r 

Edit: Saved one byte by deleting an extraneous space

That would have made The Wrath of Khan a lot more confusing.

That would have made The Wrath of Khan a lot more confusing. And "lonely" → "tingly" is a particularly satisfying substitution.

This runs the program for the text of Moby Dick and outputs the "predicted" textto stdout, and abuses stderr to write the score. I'd recommend redirecting the output to a file.