Ériu is the sovereignty goddess of Ireland. With her two sisters Fotla and Banba they make up the goddesses of Ireland. They are, in respect to my last post, aspects of the Earth Mother. In Gaelic the name for Ireland is still Éire to coincide with the goddess’s name.
Ériu and her relationship to the Morrigu is why it can be seen in the stories that Morrigan plays the role of sovereignty in certain stories. It is said that Ériu and her sisters are also the sisters of the Morrigu.
Ériu is a goddess much like the Morrigu who you should treat with a certain level of respect due to her being the sovereignty of Ireland. When dealing within an Irish Celtic pantheon respecting Ériu is paramount. Although she isn’t known for bringing about your downfall for rejection like her sister would you really want to go on a religious pilgrimage to the land of your religion and not feel welcome? Ériu can do that.
I don’t personally work with Ériu all that much. When my connection to my deities is waning I normally send some offerings her way to ensure she isn’t cutting me off from them but I generally get the “you haven’t pissed me off child don’t worry” sort of responses from her when I do this.
Maybe my next step should be to make her a normal part of my Fasting every high day…
The Mists of Vision and Memory 
Very interesting thoughts! My mind turns to Ériu at this time of year as I like to honor her. I celebrate Irish Heritage week rather St. Patrick’s Day, and I feel it’s very appropriate to pay homage to the Goddess of that land I so love.