Greetings from the Academy of Saint Gabriel!
You asked whether the given names <Aaron> and <Rachel> and the surname <Fletcher> would suit late-12th century Anglo-Saxon personae. You also asked about the usefulness of the Bible as a source of names.
Biblical names were not part of the Old English (or Anglo-Saxon) naming tradition. Before the Norman Conquest they seem to have been used only by the occasional churchman. Even for the medieval period the Old Testament isn't a good source, because only a few Old Testament names were at all common, and very few of them were women's names.
<Aaron> is occasionally found in medieval England from the 12th century on, but it was used mostly by Jews.  It's very unlikely that anyone of native Anglo-Saxon stock would have been named Aaron in the 12th century. <Rachel> is even less common. We have found just one English example of it before the 16th century, a Jew whose name was recorded in 1244.  Both names are possible in 12th century England, but both are rare, and neither would be very suitable for an Anglo-Saxon or other non-Jewish persona.
We assume that by 'Anglo-Saxon persona' you mean someone of native rather than Norman ancestry. In the late 12th century the majority of Englishmen, even those of native stock, were using names imported from the Continent, so your persona would not limit you to traditional Old English names.  For men the name <Adam> was in quite general use, and <Abraham> was used by non-Jews. For women the only Old Testament name found with any frequency in your period seems to be <Sarah>, usually in the form <Sarra>. [4, 8]
However, you may prefer to choose a name of Anglo-Saxon origin. Quite a few of these were still in use in the late 12th and early 13th centuries, though in somewhat changed forms. Here is a selection of feminine names of Old English origin. All are found in documents dated between 1150 and 1250. They are all in , where in many cases you will find other spelling variants from the same period.
Here is a selection of masculine names of Old English origin. Again, all are found in documents dated between 1150 and 1250.  The letter <v> in the starred names indicates the pronunciation; the manuscripts usually have <u>. (The two letters represented the same sound.)
You may also be interested in the lists of early 13th century names that can be found at
These are not restricted to names of Anglo-Saxon origin but do give a general picture of the given names in use at that time.
The surname <Fletcher> comes from an Old French occupational term, <flechier> or <flecher> 'maker or seller of arrows'. It is found as a byname quite early: <le fleccher> 1197 and <le Flecher> 1203. [2, 4] By the late 12th century it would not be surprising to find, say, a <Brictmer le Flecher> with a native given name and a byname of French origin.
Your query suggests that you are both planning to use the same byname. In the late 12th century it was probably still fairly unusual for a woman to be known by her husband's byname. More often she inherited one from her father or simply had one in her own right.  Many kinds of bynames are possible, but two are especially common. One is patronymic, consisting simply of the father's given name. A daughter of Ailmer might be known as <Sarra
Ailmer>, for instance. The other is locative, consisting of the
preposition <de> 'of' and a place-name, e.g., <de Norton>.
We hope that this information is helpful (and not overwhelming!). If you have further questions, we will be happy to continue to work with you.
For the Academy,
 Clark, Cecily. 'Women's Names in Post-Conquest England: Observations and Speculations', in C. Clark, _Words, Names and History_, ed. by Peter Jackson (Cambridge: D. S. Brewer, 1995).
 Fransson, Gustav. _Middle English Surnames of Occupation, 1100-1350_ (Lund: C. W. K. Gleerup, 1935).
 McKinley, Richard. _The Surnames of Oxfordshire_. English Surnames Series 3. (London: Leopard's Head Press Limited, 1977).
 Reaney, P. H., & R. M. Wilson. _A Dictionary of English Surnames_. (Oxford: Oxford University Press, 1995).
 Seror, Simon. _Les Noms des Juifs de France au Moyen Age_ (Paris: Editions du Centre National de la Recherche Scientifique, 1989).
 Selten, Bo. _The Anglo-Saxon Heritage in Middle English Personal Names: East Anglia 1100-1399_ (Lund: CWK Gleerup, 1972, 1979).
 Talan Gwynek, 'Feminine Given Names in _A Dictionary of English Surnames_' (WWW: <URL:http://www.panix.com/~mittle/names/reaney/>, 1996).
 Withycombe, E. G. _The Oxford Dictionary of English Christian Names_ (Oxford: Oxford University Press, 1984).